Coating compositions for cans and methods of coating

ABSTRACT

A coating composition for a food or beverage can that includes an emulsion polymerized latex polymer formed by combining an ethylenically unsaturated monomer component with an aqueous dispersion of a salt of an acid- or anhydride-functional polymer and an amine, preferably, a tertiary amine.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication Ser. No. 60/620,639, filed Oct. 20, 2004, the entirety ofwhich is incorporated herein by reference.

BACKGROUND

A wide variety of coatings have been used to coat the surfaces ofpackaging articles (e.g., food and beverage cans). For example, metalcans are sometimes coated using “coil coating” or “sheet coating”operations, i.e., a planar coil or sheet of a suitable substrate (e.g.,steel or aluminum metal) is coated with a suitable composition andhardened (e.g., cured). The coated substrate then is formed into the canend or body. Alternatively, liquid coating compositions may be applied(e.g., by spraying, dipping, rolling, etc.) to the formed article andthen hardened (e.g., cured).

Packaging coatings should preferably be capable of high-speedapplication to the substrate and provide the necessary properties whenhardened to perform in this demanding end use. For example, the coatingshould be safe for food contact, have excellent adhesion to thesubstrate, and resist degradation over long periods of time, even whenexposed to harsh environments.

Many current packaging coatings contain mobile or bound bisphenol A(“BPA”) or aromatic glycidyl ether compounds or PVC compounds. Althoughthe balance of scientific evidence available to date indicates that thesmall trace amounts of these compounds that might be released fromexisting coatings does not pose any health risks to humans, thesecompounds are nevertheless perceived by some people as being potentiallyharmful to human health. Consequently, there is a strong desire toeliminate these compounds from food contact coatings.

From the foregoing, it will be appreciated that what is needed in theart is a packaging container (e.g., a food or beverage can) that iscoated with a composition that does not contain extractible quantitiesof such compounds.

SUMMARY

This invention provides a coating composition for a food or beverage canthat includes an emulsion polymerized latex polymer. This polymer isformed by combining an ethylenically unsaturated monomer component withan aqueous dispersion of a salt of an acid- or anhydride-functionalpolymer (i.e., an acid group- or anhydride group-containing polymer) andan amine, preferably, a tertiary amine, and then polymerizing themonomer component.

The ethylenically unsaturated monomer component is preferably a mixtureof monomers. At least one of the monomers in the mixture is preferablyan alpha, beta-unsaturated monomer, and at least one monomer ispreferably an oxirane functional monomer. More preferably, at least oneof the monomers in the mixture is an oxirane group-containing alpha,beta-ethylenically unsaturated monomer.

In one embodiment, a method of preparing a food or beverage can isprovided. The method includes: forming a composition that includes anemulsion polymerized latex polymer, including: forming a salt of anacid- or anhydride-functional polymer and an amine in a carriercomprising water (and an optional organic solvent) to form an aqueousdispersion; combining an ethylenically unsaturated monomer componentwith the aqueous dispersion; and polymerizing the ethylenicallyunsaturated monomer component in the presence of the aqueous dispersionto form an emulsion polymerized latex polymer; and applying thecomposition including the emulsion polymerized latex polymer to a metalsubstrate prior to or after forming the metal substrate into a food orbeverage can or portion thereof.

In another embodiment, the method includes: forming a compositionincluding an emulsion polymerized latex polymer, including: forming asalt of an acid- or anhydride-functional polymer and a tertiary amine ina carrier comprising water (and an optional organic solvent) to form anaqueous dispersion; combining an ethylenically unsaturated monomercomponent comprising 0.1 wt-% to 30 wt-% of an oxirane-functional alpha,beta-ethylenically unsaturated monomer with the aqueous dispersion,based on the weight of the monomer component; and polymerizing theethylenically unsaturated monomer component in the presence of theaqueous dispersion to form an emulsion polymerized latex polymer; andapplying the composition comprising the emulsion polymerized latexpolymer to a metal substrate prior to or after forming the metalsubstrate into a food or beverage can or portion thereof.

In certain embodiments, the composition can include an organic solventin the aqueous dispersion. In certain embodiments, the method caninclude removing at least a portion of the organic solvent, if present,from the aqueous dispersion.

In certain embodiments, applying the composition to a metal substrateincludes applying the composition to the metal substrate in the form ofa planar coil or sheet, hardening the emulsion polymerized latexpolymer, and forming the substrate into a food or beverage can orportions thereof. In certain embodiments, applying the composition to ametal substrate comprises applying the composition to the metalsubstrate after the metal substrate is formed into a can or portionthereof.

In certain embodiments, forming the substrate into a can or portionthereof includes forming the substrate into a can end or a can body. Incertain embodiments, the can is a 2-piece drawn food can, 3-piece foodcan, food can end, drawn and ironed food or beverage can, beverage canend, and the like. The metal substrate can be steel or aluminum.

In certain embodiments, combining an ethylenically unsaturated monomercomponent with the aqueous dispersion includes adding the ethylenicallyunsaturated monomer component to the aqueous dispersion. Preferably, theethylenically unsaturated monomer component is added incrementally tothe aqueous dispersion.

In certain embodiments, the ethylenically unsaturated monomer componentincludes a mixture of monomers. Preferably, the mixture of monomersincludes at least one oxirane functional group-containing monomer, andmore preferably, at least one oxirane functional group-containing alpha,beta-ethylenically unsaturated monomer. In certain embodiments, theoxirane functional group-containing monomer is present in theethylenically unsaturated monomer component in an amount of at least 0.1wt-%, based on the weight of the monomer mixture. In certainembodiments, the oxirane functional group-containing monomer is presentin the ethylenically unsaturated monomer component in an amount of nogreater than 30 wt-%, based on the weight of the monomer mixture.

In certain embodiments, the methods of the present invention furtherinclude combining the emulsion polymerized latex polymer with one ormore crosslinkers, fillers, catalysts, dyes, pigments, toners,extenders, lubricants, anticorrosion agents, flow control agents,thixotropic agents, dispersing agents, antioxidants, adhesion promoters,light stabilizers, organic solvents, surfactants or combinations thereofin the coating composition.

In certain embodiments, the acid-functional polymer has a number averagemolecular weight of 1500 to 50,000.

In certain embodiments, the composition is substantially free of mobileBPA and aromatic glycidyl ether compounds. Preferably, the compositionis substantially free of bound BPA and aromatic glycidyl ethercompounds.

In certain embodiments, the acid- or anhydride-functional polymerincludes an acid- or anhydride-functional acrylic polymer, acid- oranhydride-functional alkyd resin, acid- or anhydride-functionalpolyester resin, acid- or anhydride-functional polyurethane, orcombinations thereof. Preferably, the acid- or anhydride-functionalpolymer includes an acid-functional acrylic polymer.

In certain embodiments, the amine is a tertiary amine. Preferably, thetertiary amine is selected from the group consisting of trimethyl amine,dimethylethanol amine (also known as dimethylamino ethanol),methyldiethanol amine, triethanol amine, ethyl methyl ethanol amine,dimethyl ethyl amine, dimethyl propyl amine, dimethyl 3-hydroxy-1-propylamine, dimethylbenzyl amine, dimethyl 2-hydroxy-1-propyl amine, diethylmethyl amine, dimethyl 1-hydroxy-2-propyl amine, triethyl amine,tributyl amine, N-methyl morpholine, and mixtures thereof. Preferably,the acid- or anhydride-functional polymer is at least 25% neutralizedwith the amine in water.

In certain embodiments, the ethylenically unsaturated monomer componentis polymerized in the presence of the aqueous dispersion with awater-soluble free radical initiator at a temperature of 0° C. to 100°C. In certain embodiments, the free radical initiator includes aperoxide initiator. Preferably, the free radical initiator includeshydrogen peroxide and benzoin. Alternatively, in certain embodiments thefree radical initiator includes a redox initiator system.

The present invention also provides food cans and beverage cans preparedby a method described herein.

In one embodiment, the present invention provides a food or beverage canthat includes: a body portion or an end portion including a metalsubstrate; and a coating composition disposed thereon, wherein thecoating composition includes an emulsion polymerized latex polymer,wherein the emulsion polymerized latex polymer is prepared from a saltof an acid- or anhydride-functional polymer and an amine, anethylenically unsaturated monomer component, and water.

In yet another embodiment, the present invention provides a compositionfor use in coating a food or beverage can, wherein the compositionincludes an emulsion polymerized latex polymer, wherein the emulsionpolymerized latex polymer is prepared from a salt of an acid- oranhydride-functional polymer and an amine, an ethylenically unsaturatedmonomer component, and water.

DEFINITIONS

The term “substantially free” of a particular mobile compound means thatthe compositions of the present invention contain less than 1000 partsper million (ppm) of the recited mobile compound. The term “essentiallyfree” of a particular mobile compound means that the compositions of thepresent invention contain less than 100 parts per million (ppm) of therecited mobile compound. The term “essentially completely free” of aparticular mobile compound means that the compositions of the presentinvention contain less than 5 parts per million (ppm) of the recitedmobile compound. The term “completely free” of a particular mobilecompound means that the compositions of the present invention containless than 20 parts per billion (ppb) of the recited mobile compound.

The term “mobile” means that the compound can be extracted from thecured coating when a coating (typically, approximate film weight of 1mg/cm²) is exposed to a test medium for some defined set of conditions,depending on the end use. An example of these testing conditions isexposure of the cured coating to 10 weight percent ethanol solution fortwo hours at 121° C. followed by exposure for 10 days in the solution at49° C.

If the aforementioned phrases are used without the term “mobile” (e.g.,“substantially free of XYZ compound”) then the compositions of thepresent invention contain less than the aforementioned amount of thecompound whether the compound is mobile in the coating or bound to aconstituent of the coating.

As used herein, the term “organic group” means a hydrocarbon group (withoptional elements other than carbon and hydrogen, such as oxygen,nitrogen, sulfur, and silicon) that is classified as an aliphatic group,cyclic group, or combination of aliphatic and cyclic groups (e.g.,alkaryl and aralkyl groups). The term “aliphatic group” means asaturated or unsaturated linear or branched hydrocarbon group. This termis used to encompass alkyl, alkenyl, and alkynyl groups, for example.The term “alkyl group” means a saturated linear or branched hydrocarbongroup including, for example, methyl, ethyl, isopropyl, t-butyl, heptyl,dodecyl, octadecyl, amyl, 2-ethylhexyl, and the like. The term “alkenylgroup” means an unsaturated, linear or branched hydrocarbon group withone or more carbon-carbon double bonds, such as a vinyl group. The term“alkynyl group” means an unsaturated, linear or branched hydrocarbongroup with one or more carbon-carbon triple bonds. The term “cyclicgroup” means a closed ring hydrocarbon group that is classified as analicyclic group or an aromatic group, both of which can includeheteroatoms. The term “alicyclic group” means a cyclic hydrocarbon grouphaving properties resembling those of aliphatic groups.

The term “Ar” refers to a divalent aryl group (i.e., an arylene group),which refers to a closed aromatic ring or ring system such as phenylene,naphthylene, biphenylene, fluorenylene, and indenyl, as well asheteroarylene groups (i.e., a closed ring hydrocarbon in which one ormore of the atoms in the ring is an element other than carbon (e.g.,nitrogen, oxygen, sulfur, etc.)). Suitable heteroaryl groups includefuryl, thienyl, pyridyl, quinolinyl, isoquinolinyl, indolyl, isoindolyl,triazolyl, pyrrolyl, tetrazolyl, imidazolyl, pyrazolyl, oxazolyl,thiazolyl, benzofuranyl, benzothiophenyl, carbazolyl, benzoxazolyl,pyrimidinyl, benzimidazolyl, quinoxalinyl, benzothiazolyl,naphthyridinyl, isoxazolyl, isothiazolyl, purinyl, quinazolinyl,pyrazinyl, 1-oxidopyridyl, pyridazinyl, triazinyl, tetrazinyl,oxadiazolyl, thiadiazolyl, and so on. When such groups are divalent,they are typically referred to as “heteroarylene” groups (e.g.,furylene, pyridylene, etc.)

A group that may be the same or different is referred to as being“independently” something.

Substitution is anticipated on the organic groups of the compounds ofthe present invention. As a means of simplifying the discussion andrecitation of certain terminology used throughout this application, theterms “group” and “moiety” are used to differentiate between chemicalspecies that allow for substitution or that may be substituted and thosethat do not allow or may not be so substituted. Thus, when the term“group” is used to describe a chemical substituent, the describedchemical material includes the unsubstituted group and that group withO, N, Si, or S atoms, for example, in the chain (as in an alkoxy group)as well as carbonyl groups or other conventional substitution. Where theterm “moiety” is used to describe a chemical compound or substituent,only an unsubstituted chemical material is intended to be included. Forexample, the phrase “alkyl group” is intended to include not only pureopen chain saturated hydrocarbon alkyl substituents, such as methyl,ethyl, propyl, t-butyl, and the like, but also alkyl substituentsbearing further substituents known in the art, such as hydroxy, alkoxy,alkylsulfonyl, halogen atoms, cyano, nitro, amino, carboxyl, etc. Thus,“alkyl group” includes ether groups, haloalkyls, nitroalkyls,carboxyalkyls, hydroxyalkyls, sulfoalkyls, etc. On the other hand, thephrase “alkyl moiety” is limited to the inclusion of only pure openchain saturated hydrocarbon alkyl substituents, such as methyl, ethyl,propyl, t-butyl, and the like.

The terms “comprises” and variations thereof do not have a limitingmeaning where these terms appear in the description and claims.

The terms “preferred” and “preferably” refer to embodiments of theinvention that may afford certain benefits, under certain circumstances.However, other embodiments may also be preferred, under the same orother circumstances. Furthermore, the recitation of one or morepreferred embodiments does not imply that other embodiments are notuseful, and is not intended to exclude other embodiments from the scopeof the invention.

As used herein, “a,” “an,” “the,” “at least one,” and “one or more” areused interchangeably. Thus, for example, a coating composition thatcomprises “a” polymer can be interpreted to mean that the coatingcomposition includes “one or more” polymers.

Also herein, the recitations of numerical ranges by endpoints includeall numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2,2.75, 3, 3.80, 4, 5, etc.).

The above summary of the present invention is not intended to describeeach disclosed embodiment or every implementation of the presentinvention. The description that follows more particularly exemplifiesillustrative embodiments. In several places throughout the application,guidance is provided through lists of examples, which examples can beused in various combinations. In each instance, the recited list servesonly as a representative group and should not be interpreted as anexclusive list.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

This invention provides a coating composition for use on food andbeverage cans that includes a latex polymer. The polymer is prepared inan emulsion polymerization process, preferably a free radical initiatedpolymerization process. The latex polymer can be applied to a metalsubstrate either before or after the substrate is formed into a food orbeverage can (e.g., two-piece cans, three-piece cans) or portionsthereof, whether it be a can end or can body. The latex polymers of thepresent invention are suitable for use in food contact situations andmay be used on the inside of such cans. They are particularly useful onthe interior of two-piece drawn and ironed beverage cans and on beveragecan ends.

The latex polymer is prepared by polymerizing an ethylenicallyunsaturated monomer component in an aqueous medium in the presence ofthe salt of an acid group- or anhydride group-containing polymer and anamine, preferably, a tertiary amine. The ethylenically unsaturatedmonomer component is preferably a mixture of monomers. Preferably, atleast one of the monomers in the mixture is an alpha, beta-ethylenicallyunsaturated monomer, and preferably at least one of the monomerscontains an oxirane groups. More preferably, at least one of themonomers is an oxirane group-containing alpha, beta-ethylenicallyunsaturated monomer.

The composition may optionally include crosslinkers, fillers, catalysts,dyes, pigments, toners, extenders, lubricants, anticorrosion agents,flow control agents, thixotropic agents, dispersing agents,antioxidants, adhesion promoters, light stabilizers, surfactants,organic solvents, and mixtures thereof as required to provide thedesired film properties.

In one embodiment, the coating composition is prepared by: forming asalt of an acid-functional or anhydride-functional polymer and an amine;dispersing the salt in a carrier that includes water and an optionalorganic solvent to form an aqueous dispersion; optionally removing theorganic solvent, if present, from the aqueous dispersion; combining anethylenically unsaturated monomer component with the aqueous dispersion(preferably, the ethylenically unsaturated monomer component is added tothe aqueous dispersion); and polymerizing the ethylenically unsaturatedmonomer component in the presence of the aqueous dispersion to form anemulsion polymerized latex polymer.

Preferred compositions are substantially free of mobile bisphenol A(BPA) and aromatic glycidyl ether compounds (e.g., BADGE, BFDGE, andepoxy novalacs), more preferably essentially free of these compounds,even more preferably essentially completely free of these compounds, andmost preferably completely free of these compounds. The coatingcomposition is also preferably substantially free of bound BPA andaromatic glycidyl ether compounds, more preferably essentially free ofthese compounds, most preferably essentially completely free of thesecompounds, and optimally completely free of these compounds.

The ethylenically unsaturated monomer component is preferably a mixtureof monomers that is capable of free radical initiated polymerization inaqueous medium. The monomer mixture preferably contains at least oneoxirane functional monomer, and more preferably, at least one oxiranegroup-containing alpha, beta-ethylenically unsaturated monomer.

The monomer mixture preferably contains at least 0.1 percent by weight(wt-%), more preferably at least 1 wt-%, of an oxirane group-containingmonomer, based on the weight of the monomer mixture. Typically, at least0.1 wt-% of the oxirane group-containing monomer contributes to thestability of the latex. Although not intended to be limited by theory,it is believed that this is because of the reduction in the amount ofquaternary salt formation between the oxirane species, acidgroup-containing polymer, and amine, which can cause coagulation of thelatex. In addition, at least 0.1 wt-% of the oxirane group-containingmonomer contributes to crosslinking in the dispersed particles andduring cure, resulting in better properties of coating compositionsformulated with the polymeric latices.

The monomer mixture preferably contains no greater than 30 wt-%, morepreferably no greater than 20 wt-%, even more preferably no greater than10 wt-%, and optimally no greater than 9 wt-%, of the oxiranegroup-containing monomer, based on the weight of the monomer mixture.Typically, greater than 30 wt-% of the oxirane group-containing monomerin the monomer mixture can contribute to diminished film properties.Although not intended to be limited by theory, it is believed that thisis due to embrittlement caused by an overabundance of crosslinking.

Suitable oxirane-functional monomers include monomers having a reactivecarbon-carbon double bond and an oxirane (i.e., a glycidyl) group.Typically, the monomer is a glycidyl ester of an alpha, beta-unsaturatedacid, or anhydride thereof (i.e., an oxirane group-containing alpha,beta-ethylenically unsaturated monomer). Suitable alpha,beta-unsaturated acids include monocarboxylic acids or dicarboxylicacids. Examples of such carboxylic acids include, but are not limitedto, acrylic acid, methacrylic acid, alpha-chloroacrylic acid,alpha-cyanoacrylic acid, beta-methylacrylic acid (crotonic acid),alpha-phenylacrylic acid, beta-acryloxypropionic acid, sorbic acid,alpha-chlorosorbic acid, angelic acid, cinnamic acid, p-chlorocinnamicacid, beta-stearylacrylic acid, itaconic acid, citraconic acid,mesaconic acid, glutaconic acid, aconitic acid, maleic acid, fumaricacid, tricarboxyethylene, maleic anhydride, and mixtures thereof.

Specific examples of suitable monomers containing a glycidyl group areglycidyl (meth)acrylate (i.e., glycidyl methacrylate and glycidylacrylate), mono- and di-glycidyl itaconate, mono- and di-glycidylmaleate, and mono- and di-glycidyl formate. It also is envisioned thatallyl glycidyl ether and vinyl glycidyl ether can be used as theoxirane-functional monomer. A preferred monomer is glycidyl methacrylate(“GMA”).

The oxirane-functional monomer is preferably reacted with suitable othermonomers within the monomer mixture. These can be ethylenicallyunsaturated monomer and hydroxy-functional monomers. Suitableethylenically unsaturated monomers include alkyl (meth)acrylates, vinylmonomers, alkyl esters of maleic or fumaric acid, and the like.

Suitable alkyl (meth)acrylates include those having the structure:CH₂═C(R¹)—CO—OR wherein R¹ is hydrogen or methyl, and R² is an alkylgroup preferably containing one to sixteen carbon atoms. The R² groupcan be substituted with one or more, and typically one to three,moieties such as hydroxy, halo, phenyl, and alkoxy, for example.Suitable alkyl (meth)acrylates therefore encompass hydroxy alkyl(meth)acrylates. The alkyl (meth)acrylate typically is an ester ofacrylic or methacrylic acid. Preferably, R¹ is hydrogen or methyl and R²is an alkyl group having two to eight carbon atoms. Most preferably, R¹is hydrogen or methyl and R² is an alkyl group having two to four carbonatoms.

Examples of suitable alkyl (meth)acrylates include, but are not limitedto, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate,isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate,pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate,2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, decyl(meth)acrylate, isodecyl (meth)acrylate, benzyl (meth)acrylate, lauryl(meth)acrylate, isobornyl (meth)acrylate, octyl (meth)acrylate, nonyl(meth)acrylate, hydroxyethyl acrylate (HEA), hydroxyethyl methacrylate(HEMA), hydroxypropyl (meth)acrylate (HPMA).

Difunctional (meth)acrylate monomers may be used in the monomer mixtureas well. Examples include ethylene glycol di(meth)acrylate,1,6-hexanediol di(meth)acrylate, allyl methacrylate, and the like.

Suitable vinyl monomers include styrene, methyl styrene, halostyrene,isoprene, diallylphthalate, divinylbenzene, conjugated butadiene,alpha-methylstyrene, vinyl toluene, vinyl naphthalene, and mixturesthereof. The vinyl aromatic monomers described below in connection withthe acid- or anhydride-functional polymer are also suitable for use inthe ethylenically unsaturated monomer component used to make the latexpolymer. Styrene is a presently preferred vinyl monomer, in part due toits relatively low cost.

Other suitable polymerizable vinyl monomers for use in the ethylenicallyunsaturated monomer component include acrylonitrile, acrylamide,methacrylamide, methacrylonitrile, vinyl acetate, vinyl propionate,vinyl butyrate, vinyl stearate, N-isobutoxymethyl acrylamide,N-butoxymethyl acrylamide, and the like.

The oxirane group-containing monomer preferably constitutes 0.1 wt-% to30 wt-%, and more preferably 1 wt-% to 20 wt-%, of the ethylenicallyunsaturated monomer component. The other monomer or monomers in themixture constitute the remainder of the monomer component, that is, 70wt-% to 99.9 wt-%, preferably 80 wt-% to 99 wt-%, based on total weightof the monomer mixture.

Preferably, at least 40 wt-% of the ethylenically unsaturated monomercomponent, more preferably at least 50 wt-%, will be selected from alkylacrylates and methacrylates. Preferably, at least 20 wt-%, morepreferably at least 30 wt-%, will be selected from vinyl aromaticcompounds.

Preferably, at least 5 wt-%, more preferably at least 25 wt-%, even morepreferably at least 50 wt-%, and even more preferably at least 60 wt-%,of the ethylenically unsaturated monomer component is used in making thelatex polymer. Preferably, no greater than 95 wt-%, more preferably nogreater than 90 wt-%, and even more preferably no greater than 85 wt-%,of the ethylenically unsaturated monomer component is used in making thelatex polymer. Such percentages are based on total weight ofethylenically unsaturated monomer component and salt of the acidgroup-containing or anhydride group-containing polymer (i.e.,acid-functional or anhydride-functional polymer).

Among the acid functional polymers that can be employed in preparing thelatex polymer of the present invention are virtually any acid-containingor anhydride-containing polymers that can be neutralized or partiallyneutralized with an appropriate amine to form a salt that can bedissolved or stably dispersed in the aqueous medium. The choice of theacid-containing or anhydride-containing monomer(s) is dictated by theintended end use of the coating composition and is practicallyunlimited.

The acid-containing polymer (i.e., acid-functional polymer) preferablyhas an acid number of at least 40, and more preferably at least 100,milligrams (mg) KOH per gram resin. The acid-containing polymerpreferably has an acid number of no greater than 400, and morepreferably no greater than 300, mg KOH per gram resin. Theanhydride-containing polymer, when in water, preferably has similar acidnumber ranges.

Low molecular weight polymers are preferred for certain applications ofthe present invention. Preferably, the molecular weight of the acid- oranhydride-functional polymer is no greater than 50,000 on a numberaverage molecular weight basis, and preferably no greater than 20,000.Preferably, the molecular weight of the acid- or anhydride-functionalpolymer is at least 1500 on a number average molecular weight basis, andmore preferably at least 2000.

Preferred acid- or anhydride-functional polymers that may be employedinclude acid-functional or anhydride-functional acrylic polymers, alkydresins, polyester polymers, and polyurethanes. Combinations of suchpolymers can be used if desired. Herein, the term polymer includes bothhomopolymers and copolymers (i.e., polymers of two or more differentmonomers).

Preferred acid- or anhydride-functional polymers utilized in thisinvention include those prepared by conventional free radicalpolymerization techniques. Suitable examples include those prepared fromunsaturated acid- or anhydride-functional monomers, or salts thereof,and other unsaturated monomers. Of these, preferred examples includethose prepared from at least 15 wt-%, more preferably at least 20 wt-%,unsaturated acid- or anhydride-functional monomer, or salts thereof, andthe balance other polymerizable unsaturated monomer. Examples ofco-monomers described previously apply here as well.

A variety of acid- or anhydride-functional monomers, or salts thereof,can be used; their selection is dependent on the desired final polymerproperties. Preferably, such monomers are ethylenically unsaturated,more preferably, alpha, beta-ethylenically unsaturated. Suitableethylenically unsaturated acid- or anhydride-functional monomers for thepresent invention include monomers having a reactive carbon-carbondouble bond and an acidic or anhydride group, or salts thereof.Preferred such monomers have from 3 to 20 carbons, at least 1 site ofunsaturation, and at least 1 acid or anhydride group, or salt thereof.

Suitable acid-functional monomers include ethylenically unsaturatedacids (mono-protic or diprotic), anhydrides or monoesters of a dibasicacid, which are copolymerizable with the optional other monomer(s) usedto prepare the polymer. Illustrative moiiobasic acids are thoserepresented by the structure CH₂═C(R³)—COOH, where R³ is hydrogen or analkyl radical of 1 to 6 carbon atoms. Suitable dibasic acids are thoserepresented by the formulas R⁴(COOH)C═C(COOH)R⁵ andR⁴(R⁵)C═C(COOH)R⁶COOH, where R⁴ and R⁵ are hydrogen, an alkyl radical of1-8 carbon atoms, halogen, cycloalkyl of 3 to 7 carbon atoms or phenyl,and R⁶ is an alkylene radical of 1 to 6 carbon atoms. Half-esters ofthese acids with alkanols of 1 to 8 carbon atoms are also suitable.

Non-limiting examples of useful ethylenically unsaturatedacid-functional monomers include acids such as, for example, acrylicacid, methacrylic acid, alpha-chloroacrylic acid, alpha-cyanoacrylicacid, crotonic acid, alpha-phenylacrylic acid, beta-acryloxypropionicacid, fumaric acid, maleic acid, sorbic acid, alpha-chlorosorbic acid,angelic acid, cinnamic acid, p-chlorocinnamic acid, beta-stearylacrylicacid, citraconic acid, mesaconic acid, glutaconic acid, aconitic acid,tricarboxyethylene, 2-methyl maleic acid, itaconic acid, 2-methylitaconic acid, methyleneglutaric acid, and the like, or mixturesthereof. Preferred unsaturated acid-functional monomers include acrylicacid, methacrylic acid, crotonic acid, fumaric acid, maleic acid,2-methyl maleic acid, itaconic acid, 2-methyl itaconic acid and mixturesthereof. More preferred unsaturated acid-functional monomers includeacrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleicacid, itaconic acid, and mixtures thereof. Most preferred unsaturatedacid-functional monomers include acrylic acid, methacrylic acid, maleicacid, crotonic acid, and mixtures thereof.

Nonlimiting examples of suitable ethylenically unsaturated anhydridemonomers include compounds derived from the above acids (e.g., as pureanhydride or mixtures of such). Preferred anhydrides include acrylicanhydride, methacrylic anhydride, and maleic anhydride. If desired,aqueous salts of the above acids may also be employed.

Polymerization of the monomers to form an acid- or anhydride-functionalpolymer is usually conducted by organic solution polymerizationtechniques in the presence of a free radical initiator as is well knownin the art. Although the preparation of the acid-functional oranhydride-functional polymer is conveniently carried out in solution,neat processes may be used if desired.

Besides the acid- or anhydride-functional acrylic polymers, acid- oranhydride-functional alkyd, polyester, polyurethane resins, orcombinations thereof, can also be used in the practice of the invention.Such polymers are described in U.S. Pat. Nos. 4,692,491; 3,479,310; and4,147,679. Preferably, the acid- or anhydride-functional polymers areacid-functional acrylic polymers.

In another preferred embodiment, the acid- or anhydride-functionalpolymers are polyester polymers. Examples of such polyester polymers aredisclosed in U.S. Provisional Patent Application Ser. No. 60/727,734,filed on even date herewith, entitled COATING COMPOSITIONS FORCONTAINERS AND METHODS OF COATING. Briefly, the polymers describedtherein have one or more segments of Formula I:—O—Ar—R_(n)—C(O)—O—R¹—O—C(O)—R_(n)—Ar—O—wherein each Ar is independently a divalent aryl group (i.e., an arylenegroup) or heteroarylene group; R¹ is a divalent organic group; each R isindependently a divalent organic group; and n is 0 or 1. Any one polymercan have a variety of such segments, which may be the same or different.

Preferably, R¹ provides hydrolytic stability to at least one of theadjacent ester linkages (—C(O)—O— and —O—C(O)—), and preferably to bothof them. In this context, “hydrolytic stability” means that R¹ decreasesthe reactivity (preferably, by at least half) of the adjacent esterlinkage with water compared to a —CH₂—CH₂— moiety under the sameconditions. This can be accomplished by selection of R¹ that includes asterically bulky group in proximity (preferably within two atomsdistance) to the oxygen of the ester. The polymer preferably includesmore than 70%, more preferably more than 80%, and even more preferablymore than 90%, hydrolytically stable ester linkages (based on the totalnumber of ester linkages).

In the segments of Formula I, R¹ is a divalent organic group,preferably, having at least 3 carbon atoms, more preferably, at least 4carbon atoms, even more preferably, at least 5 carbon atoms, and evenmore preferably, at least 8 carbon atoms. It is envisioned that R¹ canbe as large as desired for the particular application, which one ofskill in the art can readily determine.

In certain preferred embodiments of Formula I, R¹ is of the formula—C(R²)₂—Y_(t)—C(R²)₂—wherein each R² is independently hydrogen or an organic group (e.g., analicyclic group or a branched or unbranched alkyl group), Y is adivalent organic group, and t is 0 or 1 (preferably 1). In certainembodiments, each R² is independently hydrogen.

In certain embodiments, Y can optionally include one or more ether orester linkages. In certain embodiments, Y is a divalent saturatedaliphatic group (i.e., a branched or unbranched alkylene group), adivalent alicyclic group, or a divalent aromatic group (i.e., an arylenegroup), or combinations thereof.

In certain embodiments, Y is a divalent alkyl group (i.e., an alkylenegroup), which can be branched or unbranched, preferably having at least1 carbon atom, more preferably having at least 2 carbon atoms, even morepreferably having at least 3 carbon atoms, and even more preferablyhaving at least 6 carbon atoms. In certain embodiments, Y is a divalentalicylic group, preferably cyclohexylene. It is envisioned that Y can beas large as desired for the particular application, which one of skillin the art can readily determine.

Preferably, Y provides hydrolytic stability to at least one of the esterlinkages adjacent R¹ in Formula I. This can be accomplished by selectionof Y that includes a sterically bulky group that is in proximity(preferably within two atoms) of at least one of the ester oxygen atomsin Formula I.

In certain embodiments, R¹ has the formula —(C(R²)₂)_(s)— wherein s isat least 2, and preferably, s is at least 3, wherein each R² is asdefined above. Examples of such R¹ groups include, for example,neopentylene, butylethylpropylene, and —CH₂—CH(CH₃)—CH₂—.

In certain embodiments, Y has the formula-[Z_(w)—C(R²)₂—O—C(O)—R³—C(O)—O—C(R²)₂-]_(v)Z_(w)-,wherein w is 0 or 1, v is 1 to 10, each R² is as defined above, each R³is independently a divalent organic group, and each Z is independently adivalent organic group.

In certain embodiments, R³ is a divalent saturated aliphatic group(i.e., branched or unbranched alkylene group), a divalent alicyclicgroup, an arylene group, or combinations thereof. In certainembodiments, R³ is a (C3-C20)alkylene (branched or unbranched) group ora phenylene group.

In certain embodiments, Z is a divalent saturated aliphatic group (i.e.,branched or unbranched alkylene group), a divalent alicyclic group, adivalent aromatic group (i.e., an arylene group), or combinationsthereof.

Preferably, Z provides hydrolytic stability to at least one of the esterlinkages adjacent R¹ in Formula I and/or to an adjacent ester linkagecontained within Y. This can be accomplished by selection of Z thatincludes a sterically bulky group that is in proximity (preferablywithin two atoms distance) of at least one of the ester oxygen atoms.

In the segments of Formula I, n is preferably 0 (i.e., R is notpresent). If n is 1 and R is present, however, it is preferably a(C1-C4)alkylene group, and more preferably a (C1-C4)alkylene moiety.

In the segments of Formula I, preferably each Ar has less than 20 carbonatoms, more preferably less than 11 carbon atoms, and even morepreferably less than 8 carbon atoms. Preferably, Ar has at least 4carbon atoms, more preferably at least 5 carbon atoms, and even morepreferably, at least 6 carbon atoms.

In certain embodiments, each Ar is a phenylene group. In certainembodiments, each Ar is a phenylene group of the formula —C₆(R⁴)₄—,wherein each R⁴ is independently hydrogen, a halogen, or an organicgroup, and wherein two R⁴ groups can join to form a ring optionallycontaining one or more heteroatoms. In certain embodiments, R⁴ ishydrogen or an organic group, wherein two R⁴ groups can join to form a6-membered ring. Preferably, R⁴ is hydrogen.

Polyester polymers such as these can be made by a variety of methodsfrom compounds of Formula II:HO—Ar—R_(n)—C(O)—O—R¹—O—C(O)—R_(n)—Ar—OHwherein Ar, R, R¹, and n are as defined above. Such compounds can bemade, for example, by the esterification reaction of one mole of a diol(e.g., HO—R¹—OH such as, for example, 1,4-cyclohexane dimethanol,neopentyl glycol, 2-butyl-2-ethyl-1,3-propane diol, or2-methyl-1,3-propane diol) with two moles of an acid (e.g., 4-hydroxybenzoic acid). Alternatively, such compounds can be made, for example,by the transesterification reaction of one mole of a diol (e.g.,1,4-cyclohexane dimethanol, neopentyl glycol,2-butyl-2-ethyl-1,3-propane diol, or 2-methyl-1,3-propane diol) with twomoles of an ester (e.g., 4-hydroxy methyl benzoate, 4-hydroxy ethylbenzoate, or 4-hydroxy butyl benzoate).

Polymers of Formula I can be prepared by methods that involve advancingthe molecular weight of compounds of Formula II. In certain embodiments,compounds of Formula II (e.g., dihydric phenols) can be reacted with adiepoxide to advance the molecular weight. For example, compounds ofFormula II (e.g., dihydric phenols) can be reacted with non-BPA andnon-BPF based diepoxides much in the same manner that Bisphenol A orBisphenol F do, to create polymers that can be formulated withcrosslinkers and additives for coatings for rigid packaging. Forexample, compounds of Formula II can be reacted with a diepoxide to forma polymer that includes —CH₂—CH(OH)—CH₂— segments. Alternatively,compounds of Formula II can be reacted with epichlorohydrin to form adiepoxide analog of compounds of Formula II, which can then be reactedwith other compounds of Formula II to form a polymer that includes—CH₂—CH(OH)—CH₂— segments.

The diepoxide analogs of compounds of Formula II (e.g., glycidylpolyethers of the dihydric phenols) can be prepared by reacting therequired proportions of a compound of Formula II (e.g., dihydric phenol)and epichlorohydrin in an alkaline medium. The desired alkalinity isobtained by adding basic substances, such as sodium or potassiumhydroxide, preferably in stoichiometric excess to the epichlorohydrin.The reaction is preferably accomplished at temperatures of 50° C. to150° C. The heating is continued for several hours to effect thereaction and the product is then washed free of salt and base.Procedures for such reactions are generally well known and disclosed,for example, in U.S. Pat. No. 2,633,458.

As used in the present invention, suitable diepoxides (other than thediepoxide analogs of compounds of Formula II) are BPA- or BPF-freediepoxides, preferably with one or more ether linkages. Suitablediepoxides may be prepared by a variety of processes, for example, bythe condensation of a dihydroxy compound and epichlorohydrin. Examplesof suitable diepoxides (other than the diepoxide analogs of compounds ofFormula II) include, for example, 1,4-cyclohexanedimethanol diglycidylether (CHDMDGE), resorcinol diglycidyl ether, neopentyl glycoldiglycidyl ether, and 2-methyl-1,3-propandiol diglycidyl ether.

The resultant polymers of Formula I may be epoxy terminated or phenoxyterminated, for example. They may be made in a variety of molecularweights, such as the molecular weights of commercially availableBPA-based epoxy materials (e.g., those available under tradedesignations such as EPON 828, 1001, 1007, 1009 from ResolutionPerformance Products, Houston, Tex.). Preferred polymers of the presentinvention have a number average molecular weight (M_(n)) of at least2,000, more preferably at least 3,000, and even more preferably at least4,000. The molecular weight of the polymer may be as high as is neededfor the desired application.

Advancement of the molecular weight of the polymer may be enhanced bythe use of a catalyst in the reaction of a diepoxide (whether it be adiepoxide analog of Formula II or another diepoxide) with a compound ofFormula (II). Typical catalysts usable in the advancement of themolecular weight of the epoxy material of the present invention includeamines, hydroxides (e.g., potassium hydroxide), phosphonium salts, andthe like. A presently preferred catalyst is a phosphonium catalyst. Thephosphonium catalyst useful in the present invention is preferablypresent in an amount sufficient to facilitate the desired condensationreaction.

Alternatively, the epoxy terminated polymers of Formula I may be reactedwith fatty acids to form polymers having unsaturated (e.g., airoxidizable) reactive groups, or with acrylic acid or methacrylic acid toform free radically curable polymers.

Advancement of the molecular weight of the polymer may also be enhancedby the reaction of an epoxy terminated polymer of Formula I with asuitable diacid (such as adipic acid).

A salt (which can be a full salt or partial salt) of the acid- oranhydride-functional polymer is formed by neutralizing or partiallyneutralizing the acid groups (whether present initially in theacid-functional polymer or formed upon addition of theanhydride-functional polymer to water) of the polymer with a suitableamine, preferably a tertiary amine. The degree of neutralizationrequired to form the desired polymer salt may vary considerablydepending upon the amount of acid included in the polymer, and thedegree of solubility or dispersibility of the salt which is desired.Ordinarily in making the polymer water-dispersible, the acidity of thepolymer is at least 25% neutralized, preferably at least 30%neutralized, and more preferably at least 35% neutralized, with theamine in water.

Some examples of suitable tertiary amines are trimethyl amine,dimethylethanol amine (also known as dimethylamino ethanol),methyldiethanol amine, triethanol amine, ethyl methyl ethanol amine,dimethyl ethyl amine, dimethyl propyl amine, dimethyl 3-hydroxy-1-propylamine, dimethylbenzyl amine, dimethyl 2-hydroxy-1-propyl amine, diethylmethyl amine, dimethyl 1-hydroxy-2-propyl amine, triethyl amine,tributyl amine, N-methyl morpholine, and mixtures thereof. Mostpreferably triethyl amine or dimethyl ethanol amine is used as thetertiary amine.

The amount of the salt of the acid-functional or anhydride-functionalpolymer that is used in the polymerization is preferably at least 5wt-%, more preferably at least 10 wt-%, and even more preferably atleast 15 wt-%. The amount of the salt of the acid-functional oranhydride-functional polymer that is used in the polymerization ispreferably no greater than 95 wt-%, preferably no greater than 50 wt-%,and even more preferably no greater than 40 wt-%. These percentages arebased on total weight of polymerizable ethylenically unsaturated monomercomponent and the salt of the acid group-containing polymer.

The reaction of tertiary amines with materials containing oxiranegroups, when carried out in the presence of water, can afford a productthat contains both a hydroxyl group and a quaternary ammonium hydroxide.Under preferred conditions an acid group, an oxirane group, and an amineform a quaternary salt. This linkage is favored, as it not only linksthe polymers but promotes water dispersibility of the joined polymer. Itshould be noted that an acid group and an oxirane group may also form anester. Some of this reaction is possible, though this linkage is lessdesirable when water dispersibility is sought.

While the exact mode of reaction is not fully understood, it is believedthat a competition between the two reactions exist; however, this is notintended to be limiting. In preferred embodiments, one reaction involvesthe tertiary amine neutralized acid-functional polymer reacting with anoxirane-functional monomer or polymer to form a quaternary ammoniumsalt. A second reaction involves esterification of theoxirane-functional monomer or polymer with a carboxylic acid or salt. Inthe current invention it is believed the presence of water and level ofamine favor formation of quaternary ammonium salts over ester linkages.A high level of quatemization improves water dispersability while a highlevel of esterification gives higher viscosity and possibly gel-likematerial.

With regard to the conditions of the emulsion polymerization, theethylenically unsaturated monomer component is preferably polymerized inaqueous medium with a water-soluble free radical initiator in thepresence of the salt of the acid- or anhydride-functional polymer.

The temperature of polymerization is typically from 0° C. to 100° C.,preferably from 50° C. to 90° C., more preferably from 70° C. to 90° C.,and even more preferably from 80° C. to 85° C. The pH of the aqueousmedium is usually maintained at a pH of 5 to 12.

The free radical initiator can be selected from one or morewater-soluble peroxides which are known to act as free radicalinitiators. Examples include hydrogen peroxide and t-butylhydroperoxide. Redox initiator systems well known in the art (e.g.,t-butyl hydroperoxide, erythorbic acid, and ferrous complexes) can alsobe employed. It is especially preferred to use a mixture of benzoin andhydrogen peroxide. Persulfate initiators such as ammonium persulfate orpotassium persulfate are not preferred, as they lead to poor waterresistance properties of the cured coating.

The polymerization reaction of the ethylenically unsaturated monomercomponent in the presence of the aqueous dispersion of the polymer saltmay be conducted as a batch, intermittent, or continuous operation.While all of the polymerization ingredients may be charged initially tothe polymerization vessel, better results normally are obtained withproportioning techniques.

Typically, the reactor is charged with an appropriate amount of water,polymer salt, and free radical initiator. The reactor is then heated tothe free radical initiation temperature and then charged with theethylenically unsaturated monomer component. Preferably only water,initiator, polymer salt, and some portion of the ethylenicallyunsaturated monomer component are initially charged to the vessel. Theremay also be some water miscible solvent present. After this initialcharge is allowed to react for a period of time at polymerizationtemperature, the remaining ethylenically unsaturated monomer componentis added incrementally with the rate of addition being varied dependingon the polymerization temperature, the particular initiator beingemployed, and the type and amount of monomers being polymerized. Afterall the monomer component has been charged, a final heating is carriedout to complete the polymerization. The reactor is then cooled and thelatex recovered.

It has been discovered that coating compositions using theaforementioned latices may be formulated using one or more optionalcuring agents (i.e., crosslinking resins, sometimes referred to as“crosslinkers”). The choice of particular crosslinker typically dependson the particular product being formulated. For example, some coatingcompositions are highly colored (e.g., gold-colored coatings). Thesecoatings may typically be formulated using crosslinkers that themselvestend to have a yellowish color. In contrast, white coatings aregenerally formulated using non-yellowing crosslinkers, or only a smallamount of a yellowing crosslinker. Preferred curing agents aresubstantially free of mobile BPA and aromatic glycidyl ether compounds(e.g., BADGE, BFDGE and epoxy novalacs).

Any of the well known hydroxyl-reactive curing resins can be used. Forexample, phenoplast, and aminoplast curing agents may be used.

Phenoplast resins include the condensation products of aldehydes withphenols. Formaldehyde and acetaldehyde are preferred aldehydes. Variousphenols can be employed such as phenol, cresol, p-phenylphenol,p-tert-butylphenol, p-tert-amylphenol, and cyclopentylphenol.

Aminoplast resins are the condensation products of aldehydes such asformaldehyde, acetaldehyde, crotonaldehyde, and benzaldehyde with aminoor amido group-containing substances such as urea, melamine, andbenzoguanamine.

Examples of suitable crosslinking resins include, without limitation,benzoguanamine-formaldehyde resins, melamine-formaldehyde resins,esterified melamine-formaldehyde, and urea-formaldehyde resins.Preferably, the crosslinker employed when practicing this inventionincludes a melamine-formaldehyde resin. One specific example of aparticularly useful crosslinker is the fully alkylatedmelamine-formaldehyde resin commercially available from CytecIndustries, Inc. under the trade name of CYMEL 303.

As examples of other generally suitable curing agents are the blocked ornon-blocked aliphatic, cycloaliphatic or aromatic di-, tri-, orpoly-valent isocyanates, such as hexamethylene diisocyanate,cyclohexyl-1,4-diisocyanate, and the like.

The level of curing agent (i.e., crosslinker) required will depend onthe type of curing agent, the time and temperature of the bake, and themolecular weight of the polymer. If use, the crosslinker is typicallypresent in an amount of up to 50 wt-%, preferably up to 30 wt-%, andmore preferably up to 15 wt-%. These weight percentages are based uponthe total weight of the resin solids in the coating composition.

A coating composition of the present invention may also include otheroptional polymers that do not adversely affect the coating compositionor a cured coating composition resulting therefrom. Such optionalpolymers are typically included in a coating composition as a fillermaterial, although they can be included as a crosslinking material, orto provide desirable properties. One or more optional polymers (e.g.,filler polymers) can be included in a sufficient amount to serve anintended purpose, but not in such an amount to adversely affect acoating composition or a cured coating composition resulting therefrom.

Such additional polymeric materials can be nonreactive, and hence,simply function as fillers. Such optional nonreactive filler polymersinclude, for example, polyesters, acrylics, polyamides, polyethers, andnovalacs. Alternatively, such additional polymeric materials or monomerscan be reactive with other components of the composition (e.g., theacid-functional polymer). If desired, reactive polymers can beincorporated into the compositions of the present invention, to provideadditional functionality for various purposes, including crosslinking.Examples of such reactive polymers include, for example, functionalizedpolyesters, acrylics, polyamides, and polyethers. Preferred optionalpolymers are substantially free of mobile BPA and aromatic glycidylether compounds (e.g., BADGE, BFDGE and epoxy novalacs)

A coating composition of the present invention may also include otheroptional ingredients that do not adversely affect the coatingcomposition or a cured coating composition resulting therefrom. Suchoptional ingredients are typically included in a coating composition toenhance composition esthetics, to facilitate manufacturing, pr7ocessing,handling, and application of the composition, and to further improve aparticular functional property of a coating composition or a curedcoating composition resulting therefrom.

Such optional ingredients include, for example, catalysts, dyes,pigments, toners, extenders, fillers, lubricants, anticorrosion agents,flow control agents, thixotropic agents, dispersing agents,antioxidants, adhesion promoters, light stabilizers, surfactants, andmixtures thereof. Each optional ingredient is included in a sufficientamount to serve its intended purpose, but not in such an amount toadversely affect a coating composition or a cured coating compositionresulting therefrom.

One preferred optional ingredient is a catalyst to increase the rate ofcure. Examples of catalysts, include, but are not limited to, strongacids (e.g., dodecylbenzene sulphonic acid (DDBSA, available as CYCAT600 from Cytec), methane sulfonic acid (MSA), p-toluene sulfonic acid(pTSA), dinonyinaphthalene disulfonic acid (DNNDSA), and triflic acid),quaternary ammonium compounds, phosphorous compounds, and tin and zinccompounds. Specific examples include, but are not limited to, atetraalkyl ammonium halide, a tetraalkyl or tetraaryl phosphonium iodideor acetate, tin octoate, zinc octoate, triphenylphosphine, and similarcatalysts known to persons skilled in the art. If used, a catalyst ispreferably present in an amount of at least 0.01 wt-%, and morepreferably at least 0.1 wt-%, based on the weight of nonvolatilematerial. If used, a catalyst is preferably present in an amount of nogreater than 3 wt-%, and more preferably no greater than 1 wt-%, basedon the weight of nonvolatile material.

Another useful optional ingredient is a lubricant (e.g., a wax), whichfacilitates manufacture of metal closures by imparting lubricity tosheets of coated metal substrate. Preferred lubricants include, forexample, Carnauba wax and polyethylene type lubricants. If used, alubricant is preferably present in the coating composition in an amountof at least 0.1 wt-%, and preferably no greater than 2 wt-%, and morepreferably no greater than 1 wt-%, based on the weight of nonvolatilematerial.

Another useful optional ingredient is a pigment, such as titaniumdioxide. If used, a pigment is present in the coating composition in anamount of no greater than 70 wt-%, more preferably no greater than 50wt-%, and even more preferably no greater than 40 wt-%, based on thetotal weight of solids in the coating composition.

Surfactants can be optionally added to the coating composition to aid inflow and wetting of the substrate. Examples of surfactants, include, butare not limited to, nonylphenol polyethers and salts and similarsurfactants known to persons skilled in the art. If used, a surfactantis preferably present in an amount of at least 0.01 wt-%, and morepreferably at least 0.1 wt-%, based on the weight of resin solids. Ifused, a surfactant is preferably present in an amount no greater than 10wt-%, and more preferably no greater than 5 wt-%, based on the weight ofresin solids.

As described above, the coating compositions of the present inventionare particularly well adapted for use on food and beverage cans (e.g.,two-piece cans, three-piece cans, etc.). Two-piece cans are manufacturedby joining a can body (typically a drawn metal body) with a can end(typically a drawn metal end). The coatings of the present invention aresuitable for use in food or beverage contact situations and may be usedon the inside of such cans. They are particularly suitable for sprayapplied, liquid coatings for the interior of two-piece drawn and ironedbeverage cans and coil coatings for beverage can ends. The presentinvention also offers utility in other applications. These additionalapplications include, but are not limited to, wash coating, sheetcoating, and side seam coatings (e.g., food can side seam coatings).

Spray coating includes the introduction of the coated composition intothe inside of a preformed packaging container. Typical preformedpackaging containers suitable for spray coating include food cans, beerand beverage containers, and the like. The spray preferably utilizes aspray nozzle capable of uniformly coating the inside of the preformedpackaging container. The sprayed preformed container is then subjectedto heat to remove the residual solvents and harden the coating.

A coil coating is described as the coating of a continuous coil composedof a metal (e.g., steel or aluminum). Once coated, the coating coil issubjected to a short thermal, ultraviolet, and/or electromagnetic curingcycle, for hardening (e.g., drying and curing) of the coating. Coilcoatings provide coated metal (e.g., steel and/or aluminum) substratesthat can be fabricated into formed articles, such as 2-piece drawn foodcans, 3-piece food cans, food can ends, drawn and ironed cans, beveragecan ends, and the like.

A wash coating is commercially described as the coating of the exteriorof two-piece drawn and ironed (“D&I”) cans with a thin layer ofprotectant coating. The exterior of these D&I cans are “wash-coated” bypassing pre-formed two-piece D&I cans under a curtain of a coatingcomposition. The cans are inverted, that is, the open end of the can isin the “down” position when passing through the curtain. This curtain ofcoating composition takes on a “waterfall-like” appearance. Once thesecans pass under this curtain of coating composition, the liquid coatingmaterial effectively coats the exterior of each can. Excess coating isremoved through the use of an “air knife.” Once the desired amount ofcoating is applied to the exterior of each can, each can is passedthrough a thermal, ultraviolet, and/or electromagnetic curing oven toharden (e.g., dry and cure) the coating. The residence time of thecoated can within the confines of the curing oven is typically from 1minute to 5 minutes. The curing temperature within this oven willtypically range from 150° C. to 220° C.

A sheet coating is described as the coating of separate pieces of avariety of materials (e.g., steel or aluminum) that have been pre-cutinto square or rectangular “sheets.” Typical dimensions of these sheetsare approximately one square meter. Once coated, each sheet is cured.Once hardened (e.g., dried and cured), the sheets of the coatedsubstrate are collected and prepared for subsequent fabrication. Sheetcoatings provide coated metal (e.g., steel or aluminum) substrate thatcan be successfully fabricated into formed articles, such as 2-piecedrawn food cans, 3-piece food cans, food can ends, drawn and ironedcans, beverage can ends, and the like.

A side seam coating is described as the spray application of a liquidcoating over the welded area of formed three-piece food cans. Whenthree-piece food cans are being prepared, a rectangular piece of coatedsubstrate is formed into a cylinder. The formation of the cylinder isrendered permanent due to the welding of each side of the rectangle viathermal welding. Once welded, each can typically requires a layer ofliquid coating, which protects the exposed “weld” from subsequentcorrosion or other effects to the contained foodstuff. The liquidcoatings that function in this role are termed “side seam stripes.”Typical side seam stripes are spray applied and cured quickly viaresidual heat from the welding operation in addition to a small thermal,ultraviolet, and/or electromagnetic oven.

Other commercial coating application and curing methods are alsoenvisioned, for example, electrocoating, extrusion coating, laminating,powder coating, and the like.

Preferred coatings of the present invention display one or more of theproperties described in the Examples Section. More preferred coatings ofthe present invention display one or more of the following properties:metal exposure value of less than 3 mA; metal exposure value after dropdamage of less than 3.5 mA; global extraction results of less than 50ppm; adhesion rating of 10; blush rating of at least 7; slight or nocrazing in a reverse impact test; no craze (rating of 10) in a domeimpact test; feathering below 0.2 inch; COF range of 0.055 to 0.095; andafter paseurization or retort, a continuity of less than 20 mA.

EXAMPLES

The following examples are offered to aid in understanding of thepresent invention and are not to be construed as limiting the scopethereof. Unless otherwise indicated, all parts and percentages are byweight.

Curing Conditions

For beverage inside spray bakes, the curing conditions involvemaintaining the temperature measured at the can dome at 188° C. to 199°C. for 30 seconds.

For beverage end coil bakes, the curing conditions involve the use of atemperature sufficient to provide a peak metal temperature within thespecified time (e.g., 10 seconds at 204° C. means 10 seconds, in theoven, for example, and a peak metal temperature achieved of 204° C.).

The constructions cited were evaluated by tests as follows:

Initial Metal Exposure

This test method determines the amount the inside surface of the canthat has not been effectively coated by the sprayed coating. Thisdetermination is made thorough the use of an electrically conductivesolution (1% NaCl in deionized water). The coated can is filled withthis conductive solution, and an electrical probe is attached in contactto the outside of the can (uncoated, electrically conducting). A secondprobe is immersed in the salt solution in the middle of the inside ofthe can. If any uncoated metal is present on the inside of the can, acurrent is passed between these two probes and registers as a value onan LED display. The LED displays the conveyed currents in milliamps(mA). The current that is passed is directly proportional to the amountof metal that has not been effectively covered with coating. The goal isto achieve 100% coating coverage on the inside of the can, which wouldresult in an LED reading of 0.0 mA. Preferred coatings give metalexposure values of less than 3 mA, more preferred values of less than 2mA, and even more preferred values of less than 1 mA. Commerciallyacceptable metal exposure values are typically less than 2.0 mA onaverage.

Metal Exposure after Drop Damage

Drop damage resistance measures the ability of the coated container toresist cracks after being conditions simulating dropping of a filledcan. The presence of cracks is measured by passing electrical currentvia an electrolyte solution, as previously described in the MetalExposure section. A coated container is filled with the electrolytesolution and the initial metal exposure is recorded. The can is thenfilled with water and dropped through a tube from a specified heightonto an inclined plane, causing a dent in the chime area. The can isthen turned 180 degrees, and the process is repeated. Water is thenremoved from the can and metal exposure is again measured as describedabove. If there is no damage, no change in current (mA) will beobserved. Typically, an average of 6 or 12 container runs is recorded.Both metal exposures results before and after the drop are reported. Thelower the milliamp value, the better the resistance of the coating todrop damage. Preferred coatings give metal exposure values after dropdamage of less than 3.5 mA, more preferred valued of less than 2.5 mA,and even more preferred values of less than 1.5 mA.

Solvent Resistance

The extent of “cure” or crosslinking of a coating is measured as aresistance to solvents, such as methyl ethyl ketone (MEK, available fromExxon, Newark, N.J.) or isopropyl alcohol (IPA). This test is performedas described in ASTM D 5402-93. The number of double-rubs (i.e., oneback-and forth motion) is reported.

Global Extractions

The global extraction test is designed to estimate the total amount ofmobile material that can potentially migrate out of a coating and intofood packed in a coated can. Typically coated substrate is subjected towater or solvent blends under a variety of conditions to simulate agiven end-use. Acceptable extraction conditions and media can be foundin 21 CFR 175.300 paragraphs (d) and (e). The allowable globalextraction limit as defined by the FDA regulation is 50 parts permillion (ppm).

The extraction procedure used in the current invention is described in21CFR 175.300 paragraph (e) (4) (xv) with the following modifications toensure worst-case scenario performance: 1) the alcohol content wasincreased to 10% by weight and 2) the filled containers were held for a10-day equilibrium period at 100° F. These conditions are per the FDApublication “Guidelines for Industry” for preparation of Food ContactNotifications. The coated beverage can was filled with 10 weight percentaqueous ethanol and subjected to pasteurization conditions (150° F.) for2 hours, followed by a 10-day equilibrium period at 100° F.Determination of the amount of extractives was determined as describedin 21CFR 175.300 paragraph (e) (5), and ppm values were calculated basedon surface area of the can (no end) of 44 square inches with a volume of355 ml. Preferred coatings give global extraction results of less than50 ppm, more preferred results of less than 10 ppm, even more preferredresults of less than 1 ppm. Most preferably, the global extractionresults are optimally non-detectable.

Adhesion

Adhesion testing is performed to assess whether the coating adheres tothe coated substrate. The adhesion test was performed according to ASTMD 3359-Test Method B, using SCOTCH 610 tape, available from 3M Companyof Saint Paul, Minn. Adhesion is generally rated on a scale of 0-10where a rating of “10” indicates no adhesion failure, a rating of “9”indicates 90% of the coating remains adhered, a rating of “8” indicates80% of the coating remains adhered, and so on. Adhesion ratings of 10are typically desired for commercially viable coatings.

Blush Resistance

Blush resistance measures the ability of a coating to resist attack byvarious solutions. Typically, blush is measured by the amount of waterabsorbed into a coated film. When the film absorbs water, it generallybecomes cloudy or looks white. Blush is generally measured visuallyusing a scale of 0-10 where a rating of “10” indicates no blush and arating of “0” indicates complete whitening of the film. Blush ratings ofat least 7 are typically desired for commercially viable coatings andoptimally 9 or above.

Process or Retort Resistance

This is a measure of the coating integrity of the coated substrate afterexposure to heat and pressure with a liquid such as water. Retortperformance is not necessarily required for all food and beveragecoatings, but is desirable for some product types that are packed underretort conditions. The procedure is similar to the Sterilization orPasteurization test. Testing is accomplished by subjecting the substrateto heat ranging from 105-130° C. and pressure ranging from 0.7 to 1.05kg/cm² for a period of 15 to 90 minutes. For the present evaluation, thecoated substrate was immersed in deionized water and subjected to heatof 121° C. (250° F.) and pressure of 1.05 kg/cm² for a period of 90minutes. The coated substrate was then tested for adhesion and blush asdescribed above. In food or beverage applications requiring retortperformance, adhesion ratings of 10 and blush ratings of at least 7 aretypically desired for commercially viable coatings.

Crazing—Reverse Impact Resistance

The reverse impact measures the coated substrate's ability to withstandthe deformation encountered when impacted by a steel punch with ahemispherical head. For the present evaluation, coated substrate wassubjected to 12 in-lbs (1.36 N m) of force using BYK-Gardner “overall”Bend and Impact Tester and rated visually for micro-cracking ormicro-fracturing—commonly referred to as crazing. Test pieces wereimpacted on the uncoated or reverse side. A rating of 10 indicates nocraze and suggests sufficient flexibility and cure. A rating of 0indicates complete failure. Commercially viable coatings preferably showslight or no crazing on a reverse impact test.

Impact on Dome

Dome impact was evaluated by subjecting the dome apex of a 12 oz.beverage can to a reverse impact as described in the previous section.Craze was evaluated after impact. A rating of 10 indicates no craze andsuggests sufficient flexibility and cure. A rating of 0 indicatescomplete failure. Coatings for beverage can interiors preferably show nocraze (rating of 10) on a dome impact.

Joy Detergent Test

A 1% solution of JOY Detergent (available from Procter & Gamble) indeionized water is prepared and heated to 82° C. (180° F.). Coatedpanels are immersed in the heated solution for 10 minutes and are thenremoved, rinsed, and dried. Samples are then evaluated for adhesion andblush, as previously described. Commercially viable beverage interiorcoatings preferably give adhesion ratings of 10 and blush ratings of atleast 7, optimally at least 9, in the detergent test.

Feathering

Feathering is a term used to describe the adhesion loss of a coating onthe tab of a beverage can end. When a beverage can is opened, a portionof free film may be present across the opening of the can if the coatingloses adhesion on the tab. This is feathering.

To test feathering, a “tab” is scored on the backside of a coated panel,with the coated side of the panel facing downward. The test piece isthen pasteurized as described under the Pasteurization section below.

After pasteurization, pliers are used to bend the cut “tab” to a 90degree angle away from the coated side of the substrate. The test pieceis then placed on a flat surface, coated side down. The cut “tab” isgripped using pliers and the “tab” is pulled from the test panel at anangle of 180 degrees until it is completely removed. After removing the“tab,” any coating that extends into the opening on the test panel ismeasured. The distance of the greatest penetration (feathering) isreported in inches. Coatings for beverage ends preferably showfeathering below 0.2 inch (0.508 cm), more preferably below 0.1 inch(0.254 cm), most preferably below 0.05 inch (0.127 cm), and optimallybelow 0.02 inch (0.051 cm).

Dowfax Detergent Test

The “Dowfax” test is designed to measure the resistance of a coating toa boiling detergent solution. This is a general test run for beverageend coatings and is mainly used to evaluate adhesion. Historically, thistest was used to indicate problems with the interaction of coating tosubstrate pretreatment. The solution is prepared by mixing 5 ml ofDowfax 2A1 (product of Dow Chemical) into 3000 ml of deionized water.Typically, coated substrate strips are immersed into the boiling Dowfaxsolution for 15 minutes. The strips are then rinsed and cooled indeionized water, dried, and then tested and rated for blush and adhesionas described previously. Preferred beverage end coatings provideadhesion ratings of 10 and blush ratings of at least 4, more preferably6 or above in the Dowfax detergent test.

Sterilization or Pasteurization

The sterilization or pasteurization test determines how a coatingwithstands the processing conditions for different types of foodproducts packaged in a container. Typically, a coated substrate isimmersed in a water bath and heated for 5-60 minutes at temperaturesranging from 65° C. to 100° C. For the present evaluation, the coatedsubstrate was immersed in a deionized water bath for 45 minutes at 85°C. The coated substrate was then removed from the water bath and testedfor coating adhesion and blush as described above. Commercially viablecoatings preferably provide adequate pasteurization resistance withperfect adhesion (rating of 10) and blush ratings of at least 5,optimally at least 9.

Coefficient of Friction

Coefficient of friction (COF) is a measurement of lubricity of a coatingand is used to give an indication of how a cured coating will perform oncommercial fabrication equipment and presses. Typically, lubricants areadded to coatings requiring aggressive post application fabrication togive the appropriate lubricity.

For the present evaluation, an Altek Mobility/Lubricity Tester Model9505AE with a chart recorder was used to measure the COF of curebeverage end coatings on aluminum substrates. The instrument works bypulling a sled with steel balls attached to a loadbar across the surfaceof the coated substrate, and the COF is charted out as resistance on0-10 scale chart paper. Each unit equals 0.25 COF units. Coatings of thepresent invention are formulated to give a preferred COF range of 0.055to 0.095.

Fabrication or End Continuity

This test measures the ability of a coated substrate to retain itsintegrity as it undergoes the formation process necessary to produce abeverage can end. It is a measure of the presence or absence of cracksor fractures in the formed end. The end is typically placed on a cupfilled with an electrolyte solution. The cup is inverted to expose thesurface of the end to the electrolyte solution. The amount of electricalcurrent that passes through the end is then measured. If the coatingremains intact (no cracks or fractures) after fabrication, minimalcurrent will pass through the end.

For the present evaluation, fully converted 202 standard openingbeverage ends were exposed for a period of 4 seconds to an electrolytesolution comprised of 1% NaCl by weight in deionized water. Metalexposure was measured using a WACO Enamel Rater II, available from theWilkens-Anderson Company, Chicago, Ill., with an output voltage of 6.3volts. The measured electrical current, in milliamps, is reported. Endcontinuities are typically tested initially and then after the ends aresubjected to pasteurization or retort.

Preferred coatings of the present invention initially pass less than 10milliamps (mA) when tested as described above, more preferably less than5 mA, most preferably less than 2 mA, and optimally less than 1 mA.After paseurization or retort, preferred coatings give continuities ofless than 20 mA, more preferably less than 10 mA, even more preferablyless than 5 mA, and even more preferably less than 2 mA.

List of Raw Materials and Ingredients

The following table lists some of the raw materials and ingredients usedin the following examples. Alternative materials or suppliers may besubstituted as is appreciated to one skilled in the art

Chemical Name Trade Name Supplier Location Glacial Methacrylic Acid Rohm& Haas Philadelphia, PA Butyl Acrylate Rohm & Haas Philadelphia, PAStyrene Rohm & Haas Philadelphia, PA Benzoyl Peroxide Norac CompanyHelena, AR Butanol Dow Midland, MI Ethylene Glycol Butyl ether Butyl DowMidland, MI Cellosolve/Dowanol EB Butyl Methacrylate Rohm & HaasPhiladelphia, PA t-Butyl peroctoate Arkema Philadelphia, PA Ethylacrylate Rohm & Haas Philadelphia, PA Acrylic Acid Rohm & HaasPhiladelphia, PA Hydroxypropylmethacrylate ROCRYL 410 Rohm & HaasPhiladelphia, PA Hydroxyethyl methacrylate ROCRYL 400 Rohm & HaasPhiladelphia, PA Dimethylethanol amine Huntsman Chemical Dallas, TXGlycidyl methacrylate SR 379 Sartomer, Inc Warrington, PA Hydrogenperoxide Ashland Chemical Pittsburgh, PA Benzoin Estron Calvert City, KYN- CYLINK IBMA Cytec Ind. West Patterson, NJ Isobutoxymethacrylamidemonomer Amyl alcohol Dow Midland, MI Propylene glycol butyl DOWANOL PNBDow Midland, MI ether Secondary alcohol TERGITOL 15-S-7 Dow Midland, MIethoxylate sec-butanol Dow Midland, MI Polyethylene wax Slipayd 404Elementis Staines, UK Thermoset Phenol Based SD-912B ValsparMinneapolis, MN Phenolic Carnuba wax emulsion Michemlube 160 PFEMichelman Cincinnati, OH Isooctyl alcohol Aldrich Chemical Milwaukee, WIPolyethylene wax Lanco Glidd 5118 Lubrizol Wickliffe, OH Dipropyleneglycol Aldrich Chemical Milwaukee, WI Isophthalic aicd BP Amoco Chicago,IL Dibutyl tin oxide Fastcat 4201 Arkema Philadelphia, PA Xylene ExxonNewark, NJ Trimellitic anhydride BP Amoco Chicago, IL Iron ComplexHamp-OL 4.5% Iron Traylor Chemical Orlando, FL Erythorbic acid AldrichChemical Milwaukee, WI T-Butylhydoperoxide Trigonox A-W70 AkzoPhiladelphia, PA Ethylene glycol Ashland Chemical Pittsburgh, PA Sebacicacid Ivanhoe Indutries Tampa. FL 1,4-cyclohexane dimethanol CHDM-90Eastman Kingsport, TN 90% in water Buty Stannoic acid Fastcat 4100Arkema Philadelphia, PA 4-Hydroxybenzoic acid Acros Organics Houston, TXthrough Fisher Scientific 1,4-Cyclohexane Erisys GE-22 CVC SpecialtyMaple Shade, NJ dimethanol diglycidyl ether Chemicals EthyltriphenylCatalyst 1201 Deepwater Woodward, OK phosphonium iodide ChemicalsSuccinic ahydride JLM Marketing Tampa, FL Bisphenol A Dow Midland, MIBispenol A diglycidyl ether Epon 828 Resolution Houston, TX PerformanceProducts Methylisobutyl ketone Dow Midland, MI Dibasic ester DupontWilminton, DE Propylene glycol methyl Dowanol PM Dow Midland, MI ether

Example 1 Run 1. Preparation of Acid-Functional Acrylic

A premix of 512.6 parts glacial methacrylic acid (MAA), 512.6 partsbutyl acrylate (BA), 114.0 parts styrene, and 73.2 parts benzoylperoxide (70% water wet) was prepared in a separate vessel. A 3-literflask was equipped with a stirrer, reflux condenser, thermocouple,heating mantle, and nitrogen blanket. Ten percent of the premix wasadded to the flask along with 405.9 parts butanol and 30.6 partsdeionized water. To the remaining premix were added 496.1 parts butanoland 38.3 parts deionized water. With the nitrogen blanket flowing in theflask, the contents were heated to 93° C. At 93° C., external heatingwas stopped and the material was allowed to increase in temperature forfifteen minutes. After fifteen minutes, the batch was at 97° C., and theremaining premix was added uniformly over two hours maintaining 97° C.to 100° C. When the premix addition was complete, the premix vessel wasrinse with 5 parts butanol. The batch was held at temperature for twoand a half hours. The heating was discontinued and 317.7 parts butylcellosolve was added. The resulting acrylic prepolymer was 44.3% solids(NV), with an acid number of 313 and a Brookfield viscosity (asdetermined by ASTM D-2196) of 4,990 centipoise (cps).

Example 1 Run 2. Preparation of Acid-Functional Acrylic

A premix of 677.7 parts glacial methacrylic acid, 677.7 parts butylmethacrylate (BMA), 150.8 parts styrene, and 96.9 parts benzoyl peroxide(70% water wet) was prepared in a separate vessel. A 5-liter flask wasequipped with a stirrer, reflux condenser, thermocouple, heating mantle,and nitrogen blanket. Ten percent of the premix was added to the flaskalong with 536.9 parts butanol and 40.7 parts deionized water. To theremaining premix were added 758.1 parts butanol and 50.6 parts deionizedwater. With the nitrogen blanket flowing in the flask, the contents wereheated to 93° C. At 93° C., external heating was stopped, and thematerial was allowed to increase in temperature for ten minutes. Afterten minutes, the batch was at 98° C., and the remaining premix was addeduniformly over two hours maintaining 97° C. to 100° C. The batch washeld at temperature for three hours. The heating was discontinued andthe batch cooled. The resulting acrylic prepolymer was 49.9% NV, with anacid number of 304 and a Brookfield viscosity of 101,000 centipoise.

Example 1 Run 3. Preparation of Acid-Functional Acrylic

A premix of 802.6 parts glacial methacrylic acid, 807 parts butylmethacrylate, 178.5 parts styrene, 80.3 parts t-butyl peroctoate, 838.5parts butanol, and 59.9 parts deionized water was prepared in a separatevessel. A 5-liter flask was equipped with a stirrer, reflux condenser,thermocouple, heating mantle, and nitrogen blanket. Added to the 5 literflask were 635.8 parts butanol and 48.1 parts deionized water. The flaskwas heated to 94° C. At 94° C 12.5 parts t-butyl peroctoate were added.The batch was held for five minutes after which the premix was addedover two and a half hours. A second premix containing 59.2 parts butanoland 16.1 parts t-butyl peroctoate was prepared. When the addition of thefirst premix was complete the second premix was added over 30 minutes.Once complete, the batch was held for 30 minutes. A chase of 3.4 partst-butyl peroctoate was added and the batch held for two hours. After thetwo-hour hold time, the heat was discontinued and the batch cooled. Theresulting acrylic prepolymer was 50.1% NV, with an acid number of 292and a Brookfield viscosity of 150,000 centipoise.

Example 1 Run 4. Preparation of Acid-Functional Acrylic

A premix of 802.6 parts glacial methacrylic acid, 445.9 parts ethylacrylate, 535.1 parts styrene, 108.6 parts t-butyl peroctoate, 838.5parts butanol, and 59.9 parts deionized water was prepared in a separatevessel. A 5-liter flask was equipped with a stirrer, reflux condenser,thermocouple, heating mantle, and nitrogen blanket. Added to the 5-literflask was 635.8 parts butanol and 48.1 parts deionized water. The flaskwas heated to 94° C. At 94° C. 16.6 parts t-butyl peroctoate was added.The batch was held for five minutes after which the premix was addedover two and a half hours. A second premix containing 59.2 parts butanoland 21.2 parts t-butyl peroctoate was prepared. When the addition of thefirst premix was complete the second premix was added over 30 minutes.Once complete, the batch was held for 30 minutes. A chase of 4.6 partst-butyl peroctoate was added and the batch held for two hours. After thetwo hour hold the heat discontinued and the batch cooled. The resultingacrylic prepolymer was 49.8% NV, with an acid number of 303 and aBrookfield viscosity of 21,650 centipoise.

Example 1 Runs 5-11

Using techniques from Example 1: Run 4, the systems shown in Table 1were prepared.

TABLE 1 Acid-Functional Acrylics Ex. 1: Run 4 Run 5 Run 6 Run 7 Run 8Run 9 Run 10 Run 11 MAA 45 30 45 0 30 45 25 45 EA 25 50 45 23 0 15 30 0Styrene 30 5 10 10 25 0 25 10 BMA 0 15 0 31 0 40 0 45 AA¹ 0 0 0 36 0 0 00 BA 0 0 0 0 45 0 0 0 HPMA² 0 0 0 0 0 0 20 0 Solids 49.8% 62.8% 49.4%51.4% 55.4% 49.6% 50.5% 49.7% Acid No. 303 198 295 246 192 293 155 292Brookfield 21,650 50,000 8,730 1,100 6,660 27,800 3,532 106,000 Visc.(cps) ¹Glacial acrylic acid ²Hydroxypropyl methacrylate

Example 1 Run 12. Preparation of Acid-Functional Acrylic

A premix of 803.4 parts glacial methacrylic acid, 446.3 parts ethylacrylate (EA), 535.5 parts styrene, 153 parts benzoyl peroxide (70%water wet), 839.2 parts butanol, and 60 parts deionized water wasprepared in a separate vessel. A 5-liter flask was equipped with astirrer, reflux condenser, thermocouple, heating mantle and nitrogenblanket. To the flask, 636.3 parts butanol and 48.2 parts deionizedwater were added and heated to 97° C. to 100° C. with a nitrogen blanketflowing in the flask. The premix was added uniformly over two and a halfhours maintaining 97° C. to 100° C. When the premix was in, the premixvessel was rinsed with 59.2 parts butanol and added to the flask. Thebatch was held at temperature for two hours. The heating wasdiscontinued and the batch cooled. The resulting acrylic prepolymer was50.2% NV, with an acid number of 301 and a Brookfield viscosity of25,400 centipoise.

Example 1 Runs 13-15

Using techniques from Example 1: Run 12 the systems shown in Table 2were prepared.

TABLE 2 Acid-Functional Acrylics Example No. 1: Run 12 Run 13 Run 14 Run15 MAA 45 25 35 25 EA 25 25 25 33 Styrene 30 30 30 22 HPMA 0 20 10 20Solids 51.2% 50.2% 50.0% 50.3% Acid Number 301 171 234 169 Brookfield25,400 2,820 6,020 2,220 Viscosity (cps)

Example 2 Run 1. Preparation of Salt of Acid-Functional Acrylic

A 3-liter flask was equipped with a stirrer, reflux condenser, DeanStark Tube, thermocouple, heating mantle, and nitrogen blanket. Into theflask was added 711.5 parts of Example 1: Run 1 acrylic, 762.9 partsdeionized water, and 56.9 parts dimethyl ethanol amine (DMEA). Thecontents were heated to reflux and 553 parts were distilled from theflask. After distillation was complete, 598 parts of deionized waterwere added. The batch was cooled giving an acrylic solution at 20.3%solids and 307 acid number.

Example 2 Run 2. Preparation of Salt of Acid-Functional Acrylic

A 5-liter flask was equipped with a stirrer, reflux condenser, DeanStark Tube, thermocouple, heating mantle, and nitrogen blanket. Into theflask was added 1853 parts of Example 1: Run 2 acrylic, 2220.4 partsdeionized water, and 163.3 parts dimethyl ethanol amine. The contentswere heated to reflux and 1587 parts were distilled from the flask.After distillation was complete, 1718 parts of deionized water wereadded. The batch was cooled giving an acrylic solution at 22.2% solids,294 acid number, pH of 6.0, and a viscosity of 13 seconds (Number 4 Fordcup viscosity as determined by ASTM D-1200).

Example 2 Run 3. Preparation of Salt of Acid-Functional Acrylic

A 5-liter flask was equipped with a stirrer, reflux condenser, DeanStark Tube, thermocouple, heating mantle, and nitrogen blanket. Into theflask was added 1852.3 parts of Example 1: Run 3 acrylic, 2219 partsdeionized water, and 163 parts dimethyl ethanol amine. The contents wereheated to reflux and 1463 parts were distilled from the flask. Afterdistillation was complete, 1581 parts of deionized water were added. Thebatch was cooled giving an acrylic solution at 21.6% solids, 284 acidnumber, pH of 6.23 and a viscosity of 13 seconds (Number 4 Ford cup).

Example 2 Run 4. Preparation of Salt of Acid Functional Acrylic

A 5-liter flask was equipped with a stirrer, reflux condenser, DeanStark Tube, thermocouple, heating mantle, and nitrogen blanket. Into theflask was added 1799.2 parts of Example 1: Run 4 acrylic, 2155.9 partsdeionized water, and 158.6 parts dimethyl ethanol amine. The contentswere heated to reflux and 1541 parts were distilled from the flask.After distillation was complete, 1615 parts of deionized water wereadded. The batch was cooled giving an acrylic solution at 22.1% solids,302 acid number, pH of 6.55 and a Brookfield viscosity of 2060centipoise.

Example 2 Runs 5-15

Using techniques from Example 2: Run 4 the systems shown in Table 3 wereprepared. Each run of Example 2 used the correspondingly numbered runfrom Example 1. That is, Example 2: Run 5 used the acrylic prepolymerfrom Example 1: Run 5, etc.

TABLE 3 Acid-Functional Acrylic Salts Ex 2: Run 4 Run 5 Run 6 Run 7 Run8 Run 9 Solids 22.1% 21.4% 21.6% 22.0% 21.7% 21.3% Acid No. 302 198 291248 193 291 PH 6.55 6.49 5.96 5.95 7.30 6.26 Viscosity¹ 2,060 1,0501,770 cps — — 20 sec cps cps Ex. 2: Run 10 Run 11 Run 12 Run 13 Run 14Run 15 Solids 21.7% 21.7% 22.0% 21.3% 21.7% 22.2% Acid No. 153 300 291169 231 271 pH 7.29 6.54 6.37 6.72 — 6.67 Viscosity¹ 881 cps 15 sec 167cps 304 cps 248 cps 1900 cps ¹Brookfield viscosity values in cps andNumber 4 Ford cup viscosity values in sec.

Example 3 Run 1. Emulsion

A 1-liter flask was equipped with a stirrer, reflux condenser,thermocouple, heating mantle, and nitrogen blanket. Into the flask wereadded 313.9 parts of Example 2: Run 3 salt and 267.3 parts deionizedwater. The contents of the flask were heated to 75° C. at 280revolutions per minute (RPM). In a separate vessel, a premix of 71.4parts styrene, 116.3 parts butyl methacrylate, and 16.3 parts glycidylmethacrylate (GMA) was prepared. Once the flask was at 75° C., 10% ofthe premix was added followed by 2.04 parts benzoin and 20 partsdeionized water. The flask was heated further to 79° C. At 79° C., 2.04parts of 35% hydrogen peroxide was added and held for five minutes.After five minutes the temperature control was set at 81° C. and theremaining premix was added over a period of one hour. When the additionwas complete, 20 parts deionized water were used to rinse the residualpremix into the flask. The batch was held for ten minutes and then 0.35part benzoin, 20 parts deionized water, and 0.35 part 35% hydrogenperoxide were added. After two hours the heat was removed and the batchcooled. This gave an emulsion at 31.9% solids, 63.3 acid number, pH of6.48, and a Brookfield viscosity of 203 centipoise.

Example 3 Run 2. Emulsion

A 0.5-liter flask was equipped with a stirrer, reflux condenser,thermocouple, heating mantle, and nitrogen blanket. Into the flask wasadded 155.6 parts of Example 2: Run 4 salt and 120.6 parts deionizedwater. The contents of the flask were heated to 75° C. at 240 RPM. In aseparate vessel, a premix of 66.3 parts styrene, 19.6 parts ethylacrylate, and 7.5 parts glycidyl methacrylate was prepared. Once theflask was at 75° C., 10% of the premix was added followed by 0.91 partbenzoin and 9.4 parts deionized water. The flask was heated further to79° C. At 79° C., 0.91 part of 35% hydrogen peroxide was added and heldfor five minutes. After five minutes the temperature control was set at81° C. and the remaining premix was added over one hour. When theaddition was complete, 9.4 parts deionized water were used to rinse theresidual premix into the flask. The batch was held for ten minutes andthen 0.16 part benzoin, 9.4 parts deionized water, and 0.16 part 35%hydrogen peroxide were added. After two hours the heat was removed andthe batch cooled. This gave an emulsion at 30.9% solids, 83.8 acidnumber, pH of 6.70, and a viscosity of 40 seconds (Number 4 Ford cup).

Example 3 Run 3. Emulsion

A 1-liter flask was equipped with a stirrer, reflux condenser,thermocouple, heating mantle, and nitrogen blanket. Into the flask wasadded 311.2 parts of Example 2: Run 4 salt and 241.2 parts deionizedwater. The contents of the flask were heated to 75° C. at 270 RPM. In aseparate vessel, a premix of 112.1 parts styrene, 59.8 parts ethylacrylate, and 14.9 parts glycidyl methacrylate was prepared. Once theflask was at 75° C., 10% of the premix was added followed by 1.87 partsbenzoin and 18.8 parts deionized water. The flask was heated further to79° C. At 79° C., 1.87 parts of 35% hydrogen peroxide were added andheld for five minutes. After five minutes, the temperature control wasset at 81° C. and the remaining premix was added over one hour. When theaddition was complete, 18.8 parts deionized water were used to rinse theresidual premix into the flask. The batch was held for ten minutes andthen 0.32 part benzoin, 18.8 parts deionized water, and 0.32 part 35%hydrogen peroxide were added. After two hours, the heat was removed andthe batch cooled. This gave an emulsion at 31.8% solids, 76.7 acidnumber, pH of 6.67, and a viscosity of 28 seconds (Number 4 Ford cup).

Example 3 Run 4. Emulsion

A 5-liter flask was equipped with a stirrer, reflux condenser,thermocouple, heating mantle, and nitrogen blanket. Into the flask wasadded 1525.0 parts of Example 2: Run 4 salt and 1219.1 parts deionizedwater. The contents of the flask were heated to 70° C. at 250 RPM. In aseparate vessel a premix of 380.4 parts styrene, 278.3 parts butylacrylate (BA), 194.9 parts butyl methacrylate, and 74.2 parts glycidylmethacrylate was prepared. Once the flask was at 70° C., 10% of thepremix was added followed by 9.29 parts benzoin and 92.9 parts deionizedwater. The flask was heated further to 79° C. At 79° C., 9.29 parts of35% hydrogen peroxide were added and held for five minutes. After fiveminutes the temperature control was set at 81° C. and the remainingpremix was added over one hour. When the addition was complete, 92.9parts deionized water were used to rinse the residual premix into theflask. The batch was held for ten minutes and then 1.59 parts benzoin,92.9 parts deionized water, and 1.59 parts 35% hydrogen peroxide wereadded. The batch was held for 45 minutes and then 0.52 part benzoin and0.52 part 35% hydrogen peroxide were added. After two hours the heat wasremoved and the batch cooled. This gave an emulsion at 31.4% solids,64.1 acid number, pH of 6.95, and a viscosity of 22 seconds (Number 4Ford cup).

Example 3 Run 5. Emulsion

A 12-liter flask was equipped with a stirrer, reflux condenser,thermocouple, heating mantle, and nitrogen blanket. Into the flask wasadded 3886.5 parts of Example 2: Run 4 salt and 3022.5 parts deionizedwater. The contents of the flask were heated to 70° C. at 235 RPM. In aseparate vessel, a premix of 771.25 parts styrene, 933.75 parts butylacrylate, 537.5 parts butyl methacrylate, and 93.75 parts glycidylmethacrylate was prepared. Once the flask was at 70° C., 23.38 partsbenzoin and 116.25 parts deionized water followed by 10% of the premixwere added. The flask was heated further to 79° C. At 79 ° C., 23.38parts of 35% hydrogen peroxide and 116.25 parts deionized water wereadded and held for five minutes. After five minutes the temperaturecontrol was set at 81° C. and the remaining premix was added over onehour. When the addition was complete, 232.5 parts deionized water wereused to rinse the residual premix into the flask. The batch was held forten minutes and then 4.0 parts benzoin, 232.5 parts deionized water, and4.0 parts 35% hydrogen peroxide were added. The batch was held for 45minutes and then 1.25 parts benzoin and 1.25 parts 35% hydrogen peroxidewere added. After two hours the heat was removed and the batch cooled.This gave an emulsion at 31.4% solids, 72.4 acid number, pH of 7.05, anda viscosity of 32 seconds (Number 4 Ford cup).

Example 3 Runs 6-10

Using the process outlined in Example 3: Run 4 the Emulsions shown inTable 4 were prepared.

TABLE 4 Emulsions Example 3: Run 4 Run 6 Run 7 Run 8 Run 9 Run 10Acrylic salt Ex. 2: Run 4 Ex. 2: Run 4 Ex. 2: Run 4 Ex. 2: Run 4 Ex. 2:Run 4 Ex. 2: Run 4 Monomers Styrene 41.0 39.0 42.0 43.5 43.5 45.0 BA30.0 53.0 54.0 54.5 54.5 55.0 BMA 21.0 0.0 0.0 0.0 0.0 0.0 GMA 8.0 8.04.0 2.0 2.0 0.0 Emulsion Comments Good Good Good White-High White-LowEmulsion Appearance Appearance Appearance Viscosity Conversion SeparatedSolids 31.4% 31.3% 31.5% 31.7% 28.6% 31.2% Viscosity 22 sec 51 sec 103sec — 22 sec — (No. 4 Ford Cup) Brookfield — 230 cps 610 cps 25,000 cps— — Viscosity pH 6.95 7.05 6.88 — 6.65 —

This resin series showed that as the GMA level decreased, acceptableemulsions became more difficult to produce.

Example 3 Runs 11-18

A design experiment using Example 2: Run 9 as the acid functionalacrylic salt and the process outlined above was prepared and is depictedin Table 5.

TABLE 5 Emulsion Design Experiment Example 3: Run 11 Run 12 Run 13 Run14 Run 15 Run 16 Run 17 Run 18 Acrylic/Monomer 73/27 65/35 Ratio MonomerMonomer Monomer Monomer Composition 1 Composition 2 Composition 1Composition 2 GMA Level Low High Low High Low High Low High MonomersStyrene 42 39 33 33 43 41 33 33 BA 54 53 40 41 54 53 40 40 BMA 0 0 23 180 0 24 21 GMA 4 8 4 8 3 6 3 6 Solids 32.0% 31.3% 31.6% 31.9% 31.6% 32.0%31.7% 32.0% Viscosity — 63 sec — — 35 sec 210 sec 42 sec — (No. 4 FordCup) Brookfield 10,000 — 10,000 695 — — — 1,384 Viscosity (cps) AcidNumber 74.7 72.9 74.9 70.2 101 96.1 101 96.5

The latices from Table 5 were tested without further modification orformulation, and the results are shown in Table 6. Each composition wasdrawn down onto Alcoa ALX aluminum at a film weight of 7-8 milligramsper square inch (msi) (1.1-1.25 milligrams per square centimeter(mg/cm²)) and cured for 10 seconds to achieve a 420° F. (215° C.) peakmetal temperature in a gas fired coil oven.

TABLE 6 Beverage End Film Performance Waterbased Ex. 3: Run Ex. 3: RunEx. 3: Run Ex. 3: Run Ex. 3: Run Ex. 3: Run Ex. 3: Run Ex. 3: RunControl¹ 11 12 13 14 15 16 17 18 Craze None None None None None NoneSlight None None MEK 19 5 6 3 7 5 6 4 8 Resistance Feathering⁴ 0.3430.013 0.020 0.071 0.003 0.020 0.013 0.030 0.013 Water Retort² Blush 9.510 9.5 9.5 9.5 9 10 8 10 Adhesion 10 10 10 10 10 10 10 10 10Pasteurization³ Blush 10 10 10 10 10 10 10 10 10 Adhesion 10 10 10 10 1010 10 10 10 End Continuity Initial 0 0.22 25.3 11.5 57.8 17.7 133.5 27.5132.2 After Retort² 8.4 31.8 Not Tested 31.7 Not Tested Not Tested NotTested 34.3 Not Tested ¹Commercially available beverage end coating fromValspar coded 13Q80AG. ²90 minutes at 121° C. (250° F.). ³30 minutes at85° C. (185° F.). ⁴Performed after a 45 minutes at 85° C. (185° F.)pasteurization. Measured in centimeters.

Example 3 Runs 5b and 19-25

A design experiment using Example 2: Run 4 as the acid functionalacrylic salt and the process outlined above was prepared and is depictedin Table 7. Example 3: Run 5b was included as one of the variables andwas a repeat of Run 5.

TABLE 7 Emulsion Design Experiment Example 3: Run 19 Run 20 Run 5b Run21 Run 22 Run 23 Run 24 Run 25 Acrylic/Monomer 73/27 65/35 Ratio MonomerMonomer Monomer Monomer Composition 1 Composition 2 Composition 1Composition 2 GMA Level Low High Low High Low High Low High MonomersStyrene 42 39 33 33 43 41 33 33 BA 54 53 40 41 54 53 40 40 BMA 0 0 23 180 0 24 21 GMA 4 8 4 8 3 6 3 6 Solids 31.5% 31.6% 31.6% 31.4% 31.3% 31.6%31.5% 31.7% Viscosity 55 sec 60 sec 50 sec 56 sec 106 sec — 70 sec —(No. 4 Ford Cup) Brookfield — — — — — 2,624 — 3,000 Viscosity (cps) AcidNumber 71.9 73.0 69.0 68.3 95.4 92.5 94.7 98.0

The lattices from Table 7 were tested without further modification orformulation, and the results are shown in Table 8. Each composition wasdrawn 10 down onto Alcoa ALX aluminum at a film weight of 7-8 msi(1.1-1.25 mg/cm²) and cured for 10 seconds to achieve a 420° F. (215°C.) peak metal temperature in a gas fired coil oven.

TABLE 8 Beverage End Film Performance Waterbased Ex. 3: Run Ex. 3: RunEx. 3: Run Ex. 3: Run Ex. 3: Run Ex. 3: Run Ex. 3: Run Ex. 3: RunControl¹ 19 20 5b 21 22 23 24 25 Craze None None None None None NoneSlight None Yes MEK 19 4 7 4 10 6 11 4 6 Feathering⁴ 0.343 0.064 0.0510.038 0.033 0.056 0.013 0.046 0.013 Water Retort² Blush 9.5 9.5 9.5 1010 9.5 10 7 9.5 Adhesion 10 10 10 10 10 10 10 10 10 Pasteurization³Blush 10 10 10 10 10 10 10 10 10 Adhesion 10 10 10 10 10 10 10 10 10 EndContinuity Initial 0 5.5 2.6 6.0 12.3 20.2 61.2 1.9 93.6 After Retort²8.4 23.5 143 23.4 134.0 78.8 Not Tested 52.5 Not Tested ¹Commerciallyavailable beverage end coating from Valspar coded 13Q80AG. ²90 minutesat 121° C. (250° F.). ³30 minutes at 85° C. (185° F.). ⁴Performed aftera 45 minutes at 85° C. (185° F.) pasteurization. Measured incentimeters.

Example 3 Runs 26-33

A design experiment using Example 2: Run 11 as the acid functionalacrylic salt and the process outlined above was prepared and is depictedin Table 9.

TABLE 9 Emulsion Design Experiment Example 3: Run 26 Run 27 Run 28 Run29 Run 30 Run 31 Run 32 Run 33 Acrylic/Monomer 73/27 65/35 Ratio MonomerMonomer Monomer Monomer Composition 1 Composition 2 Composition 1Composition 2 GMA Level Low High Low High Low High Low High MonomersStyrene 42 39 33 33 43 41 33 33 BA 54 53 40 41 54 53 40 40 BMA 0 0 23 180 0 24 21 GMA 4 8 4 8 3 6 3 6 Solids 31.0% 31.8% 31.5% 31.4% 30.9% 31.3%31.4% 31.6% Viscosity 40 sec 48 sec — 17 sec 14 sec 16 sec 14 sec 16 sec(No. 4 Ford Cup) Brookfield — — 17,000 — — — — — Viscosity (cps) AcidNumber 73.5 68.7 71.2 68.6 97.0 93.9 99.3 93.9

The latices from Table 9 were tested without further modification orformulation, and the results are shown in Table 10. Each composition wasdrawn down onto Alcoa ALX aluminum at a film weight of 7-8 msi (1.1-1.25mg/cm²) and cured for 10 seconds to achieve a 420° F. (215° C.) peakmetal temperature in a gas fired coil oven.

TABLE 10 Beverage End Film Performance of Emulsion DOE C Waterbased Ex.3: Run Ex. 3: Run Ex. 3: Run Ex. 3: Run Ex. 3: Run Ex. 3: Run Ex. 3: RunEx. 3: Run Control¹ 26 27 28 29 30 31 32 33 Craze None Slight None NoneYes Yes Yes Yes Yes MEK 19 7 8 3 12 3 5 7 6 Feathering⁴ 0.343 0.0460.043 0.013 0.025 0.013 0.013 0.020 0.013 Water Retort² Blush 9.5 9.510.0 9.5 10 2 10 3 9.5 Adhesion 10 10 10 10 10 10 10 10 10Pasteurization³ Blush 10 10 10 10 10 10 10 10 10 Adhesion 10 10 10 10 1010 10 10 10 End Continuity Initial 0 82.4 107.4 12.2 215.6 178.9 315.9161.5 336.9 After Retort² 8.4 Not Tested Not Tested Not Tested NotTested Not Tested Not Not Not Tested Tested Tested ¹Commerciallyavailable beverage end coating from Valspar coded 13Q80AG. ²90 minutesat 121° C. (250° F.). ³30 minutes at 85° C. (185° F.). ⁴Performed aftera 45 minutes at 85° C. (185° F.) pasteurization. Measured incentimeters.

The following are some of the conclusions drawn from results of theemulsion DOEs shown in Tables 5 through 10. The non styrene-containingacrylic stabilizer polymer from Example 2: Run 9 produced higherviscosity emulsions, which are less desirable for some end uses. Thecomposition from Example 2: Run 4 gave better overall film performance.In general, a higher acrylic polymer/monomer ratio tended to give poorerfilm integrity (continuities). Higher GMA levels in the emulsion monomermix tended to give higher emulsion viscosities and greater increases infilm continuity mAs after retort. Little difference was noticed betweenthe various co-monomer compositions, so there is latitude to vary theoverall emulsion monomer composition.

Example 3 Runs 34-35

A series of emulsions, shown in Table 11 were prepared using a monomerto acid functional acrylic ratio of 73/27 solids/solids. These systemswere prepared using the process outlined in Example 3: Run 5 usingExample 2: Run 4 as the acid functional acrylic salt.

TABLE 11 Emulsion GMA Level Study Example 3: Run 5b Run 34 Run 35 GMALevel   4%   12%   20% Monomers Styrene 33 33 33 BA 40 42 44 BMA 23 13 3GMA  4 12 20 Solids 31.6% 31.8% 32.0% Viscosity (No. 4 Ford cup) 50 sec— — Brookfield Visc. (cps) — 1,070   33,950    Acid Number   69.0   59.5  44.9

It can be seen that as the glycidyl methacrylate level was increased,the resulting acid number decreased, indicating the GMA consumed some ofthe acid groups on the acrylic polymer stabilizer.

Example 3 Runs 36-42

A series of emulsions, shown in Table 12, were prepared using a monomerto acid functional acrylic ratio of 73/27 solids/solids. These systemswere prepared using the process outlined in Example 3: Run 5b usingExample 2: Run 10 as the acid functional acrylic salt. This acryliccontains hydroxyl functionality that may theoretically co-react with theIBMA during cure.

TABLE 12 Effect of IBMA in Emulsions Example 3: Run 36 Run 37 Run 38 Run39 Run 40 Run 41 Run 42 IBMA Level 0% 4% 5% 6% 7% 8% 12% MonomersStyrene 33 26 26 26 26 26 26 BA 40 45 46 46 46 47 48 BMA 23 21 19 18 1715 10 GMA 4 4 4 4 4 4 4 IBMA¹ 0 4 5 6 7 8 12 Solids % 31.4% 31.6% 30.9%30.4% 30.4% 30.0% 29.8% Viscosity (No. 4 22 sec 17 sec 18 sec 16 sec 16sec 16 sec 17 sec Ford Cup) Acid Number 38.1 40.1 40.9 39.5 40.5 41.040.4 ¹N-Isobutoxymethyl acrylamide

The latices from Table 12 were tested without further modification orformulation, and the results are shown in Table 13. Each composition wasdrawn down onto Alcoa ALX aluminum at a film weight of 7-8 msi (1.1-1.25mg/cm²) and cured for 10 seconds to achieve a 420° F. (215° C.) peakmetal temperature in a gas fired coil oven.

TABLE 13 Beverage End Continuities (IBMA Level) Example 3: Run Run 36 37Run 38 Run 39 Run 40 Run 41 Run 42 IBMA 0% 4% 5% 6% 7% 8% 12% Level EndContinuity Initial 3 1.5 1.1 1.0 0.4 0.9 0.7 After 19 12 4.3 6.5 6.6 9.331 Retort¹ ¹90 minutes at 250° F. (121° C.).

Results from Table 13 indicate the optimum level of IBMA in the emulsionmonomer composition is around 5%, when used in conjunction with hydroxylfunctionality in the acrylic polymer stabilizer.

Example 4 Runs 1-2. Spray Application

The water-based emulsion of Example 3: Run 4 was successfully formulatedinto a spray applied coating for the interior of beer/beverage aluminumcans. The product was formulated with or without additional surfactant,as described in Table 14.

TABLE 14 Beverage Inside Spray Coating Compositions Example 4: Run 1 Run2 Composition (parts) Example 3: Run 4 62 65 Butanol 6 5 ButylCellosolve 3 0 Amyl Alcohol 1 0 Dowanol PNB¹ 0 5 TERGITOL 15-S-7² 0 1Deionized Water 28 24 Formulation Solids, % 20 21 Viscosity, No. 4 Fordcup 20 sec 30 sec VOC, kg/l - H₂O 0.358 0.358 ¹Commercially availablefrom Dow Chemical. ²Commercially available surfactant from Dow Chemical.

These formulations were sprayed at typical laboratory conditions at 120milligram per can (mg/can) to 130 mg/can coating weight for theapplication of interior beverage coatings, and cured at 188° C. to 199°C. (measured at the can dome) for 30 seconds through a gas oven conveyorat typical heat schedules for this application. The film propertiesshown in Table 15 were achieved.

TABLE 15 Inside Spray Film Properties Example 4: Run 1 Run 2 MetalExposures Initial 2 mA 3 mA After drop damage 2 mA 7 mA MEK resistance<2 <2 Water retort¹ Blush None None Adhesion Excellent Excellent Globalextraction² 0.25 ppm 3.8 ppm ¹90 minutes at 250° F. (121° C.). ²2 hoursat 150° F. in 90% aqueous ethanol.

The cured films displayed excellent resistance properties and low globalextractions despite the fact that their solvent resistance as determinedby MEK rubs is low. The higher global extraction result for Example 4:Run 2 was determined to be due to the surfactant present.

Example 4 Runs 3-4. Spray Application

The water-based emulsion of Example 3: Run 4 and Example 3: Run 7 weresuccessfully formulated into spray applied coatings for the interior ofbeer/beverage aluminum cans. Coating compositions are shown in Table 16.

TABLE 16 Inside Spray Coating Compositions Example 4: Run 3 Run 4Composition (Parts) Example 3 Run 4 62.8 0 Example 3 Run 7 0 62.8Deionized water 22.1 22.1 Butanol 5.9 5.3 Butyl Cellosolve 2.9 2.9 Amylalcohol 1.3 1.3 Secondary butanol 0 0.5 Deionized water 5.0 5.1 Dimethylethanolamine As Needed As Needed Formulation solids 20.7% 20.4%Viscosity (No. 4 Ford cup) 20 sec 16 sec

These formulations were sprayed at typical laboratory conditions at 120mg/can to 130 mg/can (12-ounce) coating weight for the application ofinterior beverage coatings, and cured at 188° C. to 199° C. (measured atthe can dome) for 30 seconds through a gas oven conveyor at typical heatschedules for this application. The film properties shown in Table 17were achieved, using a commercial epoxy-acrylate coating as a control.

TABLE 17 Inside Spray Film Properties Waterbased Example 4: Example 4:Control¹ Run 3 Run 4 Coating weight, mg/can 124 123 121 Metal ExposuresInitial 0.9 mA 2.2 mA 0.5 mA After drop damage 1.3 mA 2.9 mA 1.2 mA MEKResistance 20-50 2-5 <1 Impact on Dome 10 10 10 IsopropanolResistance >100 >100 5-10 Water retort² Blush 7 10 10 Adhesion 10 10 10Joy Detergent Test Blush 7 10 10 Adhesion 10 10 10 Global extractions³<0.1 ppm⁴ <0.1 ppm⁴ <0.1 ppm⁴ ¹Commercially available inside beveragecan coating from Valspar coded 10Q45AF. ²90 minutes at 250° F. (121°C.). ³2 hours at 150° F. in 90% aqueous ethanol. ⁴Below the currentdetection limit.

As can be seen in Table 17, the coatings of the present inventioncompare favorably to the commercial epoxy-acrylate coating, and there isa substantial benefit for retort resistance.

Example 5 Run 1. Beverage End Coil Coating

In ajar with an agitator, 483.25 parts of Example 3: Run 5 emulsion wasstirred with 16.75 parts SLIPAYD 404 wax. The mixture was stirred for 10minutes to make it uniform. The mixture was then filtered. The mixturewas approximately 31% solids. The mixture was applied at 7-8 milligramsper square inch (msi) (1.1-1.25 mg/cm²) on ALX Alcoa aluminum and bakedfor 10 seconds (sec) to achieve a 400° F. (204° C.) peak metaltemperature in a coil oven. It was also applied at 7-8 msi (1.1-1.25mg/cm²) on ALX Alcoa aluminum and baked for 10 seconds to achieve a 435°F. (224° C.) peak metal temperature in a coil oven. Film properties areshown in Table 18.

TABLE 18 Beverage End Film Properties Waterbased Control¹ Example 5 Run1 10 sec to 10 sec to 10 sec to 10 sec to achieve achieve achieveachieve 400° F. 435° F. 400° F. 435° F. Bake (204° C.) (224° C.) (204°C.) (224° C.) MEK Res. 23 35 4 4 Feathering² 0.500 0.193 0.018 0.010Dowfax³ Blush 4 9 4 9 Adhesion 10 10 10 10 Pasteurization⁴ Blush 6 9 510 Adhesion 10 10 10 10 Water Retort⁵ Blush 6.5 10 5.5 10 Adhesion 10 1010 10 End Continuities Initial After Initial After Initial After InitialAfter Pasteurization⁴ 0.13 0.33 0.06 0.28 2.76 21.35 1.5 17.9 WaterRetort⁵ 0.016 2.22 0.06 0.52 4.16 22.9 1.4 17.55 ¹Commercially availablebeverage end coating from Valspar coded 13Q80AG. ²Performed after a 45minutes at 85° C. (185° F.) pasteurization. Measured in centimeters. ³15minutes at 100° C. (212° F.). ⁴30 minutes at 85° C. (185° F.). ⁵90minutes at 121° C. (250° F.).

Example 5 Runs 2-4 Beverage End Coatings

Using the process of Example 5: Run 1, the formulations shown in Table19 were prepared to investigate the effect of GMA level on endcontinuities. Each formula was applied at 7-8 milligrams per square inch(msi) (1.1-1.25 mg/cm²) on ALX Alcoa aluminum and baked for 10 secondsto achieve a 420° F. (215° C.) peak metal temperature in a coil oven.End continuities are shown in Table 20.

TABLE 19 Effect of GMA Level Example 5: Run 2 Run 3 Run 4 Example 3 Run5 95.7 0 0 Example 3 Run 34 0 95.7 0 Example 3 Run 35 0 0 95.7 Phenolic¹2.3 2.3 2.3 SLIPAYD 404 1.5 1.5 1.5 Michem Lube 0.5 0.5 0.5 160 PFE²Water/Solvent³ To 23% Solids To 23% Solids — Deionized Water — — To 23%Solids ¹A phenol-formaldehyde phenolic at 50% in water, prepared byreacting 2.3 moles of formaldehyde with 1 mole of phenol. ²Commerciallyavailable lubricant from Michelman Inc. ³1:1 Blend of deionized waterand isopropyl alcohol.

TABLE 20 Effect of GMA Level on Beverage End Performance Example 5: Run2 Run 3 Run 4 GMA Level 4% 12% 20% End Continuities Initial  2  49 149After Retort¹ 21 193 304 ¹90 minutes at 121° C. (250° F.).

As can be seen by the data in Table 20, lower GMA levels appear toprovide better film integrity on fabricated ends, especially after aretort.

Example 5 Run 5 Beverage End Coating

Using the process of Example 5: Run 1, the formulation shown in Table 21was prepared. The formula was applied at 7-8 milligrams per square inch(msi) (1.1-1.25 mg/cm²) on ALX Alcoa aluminum and baked for 10 secondsto achieve 400° F. (204° C.) and 420° F. (215° C.) peak metaltemperatures in a coil oven. Film and end performance properties areshown in Table 22. This material contains 4% GMA and 5% IBMA in theemulsion monomer mix and an acrylic composition with hydroxylfunctionality.

TABLE 21 Beverage End Formulation Example 5 Run 5 Composition Example 3,Run 38 90.80 Dowanol PNP¹ 2.425 Dowanol DPNB¹ 2.425 Isooctyl Alcohol1.54 Michem Lube 160 PFE 0.57 Lanco Glidd 5118² 2.24 Solids (%)27.5-29.5 Viscosity (No. 4 Ford Cup) 20 sec-30 sec ¹Commerciallyavailable from Dow Chemical ²Commercially available lubricant fromLubrizol Corp.

TABLE 22 Film Performance of Beverage End Formulation Water BaseControl¹ Example 5 Run 5 10 sec to 10 sec to 10 sec to 10 sec to achieveachieve achieve achieve 400° F. 420° F. 400° F. 420° F. Bake (204° C.)(215° C.) (204° C.) (215° C.) MEK Res. 34 40 10 8 Feathering⁴ 0.1780.094 0.074 0.038 Pencil 3H-4H 3H HB HB Hardness COF 0.068 0.076 0.0680.075 Pasteurization² Blush 10 10 9 10 Adhesion 10 10 10 10 WaterRetort³ Blush 9 10 8 9 Adhesion 10 10 10 10 End Continuities InitialAfter Initial After Initial After Initial After Pasteurization² 0.0 0.11.1 17.6 0.5 0.7 0.5 4.3 Water Retort³ 0.05 0.15 1.4 11.2 0.15 0.35 0.7810.5 ¹Commercially available beverage end coating from Valspar coded13Q80AG. ²30 minutes at 85° C. (185° F.). ³90 minutes at 121° C. (250°F.). ⁴Performed after 45 minutes at 85° C. (185° F.) pasteurization.Measured in centimeters.

Results from Table 22 show that a beverage end formulation of thepresent invention can give similar performance to a commercialepoxy-based waterborne beverage end coating even with lower solventresistance as measured by MEK double rubs. There is also an addedbenefit of improved feathering resistance.

Example 6 Latex with Polyester Stabilizer

Example 6 is designed to illustrate the use of a differentacid-functional polymer salt as the stabilizer for an emulsion of thepresent invention.

Stage A

A 2-liter flask was equipped with a stirrer, packed colomn, Dean Starktrap, reflux condenser, thermocouple, heating mantle and nitrogenblanket. To the flask 700.1 parts dipropylene glycol and 700.1 partsisophthalic acid were added. Under a nitrogen blanket, the contents wereheated to 125° C. At 125° C., 1.05 parts FASCAT 4201 was added. Thetemperature was increased to remove water. At 210° C., water wasbeginning to collect. After an acid number of 5.2 was obtained, 37 partsof xylene was added to aid in the removal of water. An acid number of0.9 was obtained, and a portion of the product was used in Stage B.

Stage B

The material from Stage A (599.8 parts) was placed in a 2-liter flask.The temperature was set at 112° C. and 82 parts trimellitic anhydridewas added. The material was heated to 232° C., and water was removed.After an acid number of 48.4 was obtained, a portion of the material wasused in Stage C.

Stage C

The material from Stage B (198.8 parts) was added to a 2-liter flask,and 40 parts of DOWANOL PNP were added. The material was adjusted to 74°C., and slow addition of deionized water (200 parts) was initiated.After about 30 parts of water were added, 7.6 parts dimethylethanolamine were introduced. When about 150 parts of the deionizedwater were in, heating was halted (the temperature was at 80° C.) and2.4 parts dimethyl ethanolamine were added. After the entire charge ofdeionized water was complete, the viscosity was visually high and 200additional parts deionized water was added. The material was allowed toslowly cool while additional dimethyl ethanolamine was addedincrementally to increase the pH to 6.6. The resulting product was 29.7%solids with an acid number of 53.9.

Stage D

A 500-milliliter flask was equipped with a stirrer, reflux condenser,thermocouple, heating mantle, and nitrogen blanket. Into the flask wasadded 93.2 parts of the Stage C material and 179 parts deionized water.While the contents of the flask were being heated to 50° C. at 240 RPM,2 drops of HAMP-OL 4.5% Iron and 1.11 parts erythorbic acid were added.In a separate vessel a premix of 28.8 parts styrene, 50.9 BA, 21.0 partsBMA, 5.6 parts IBMA, 4.5 parts GMA and 1.11 parts TRIGONOX A-W70 werepremixed. Once the flask was at 52° C., 10% of the premix was added andheld for five minutes. After five minutes, the temperature control wasset for 50° C. and the remaining premix was added over one hour. Whenthe addition was complete, 15.0 parts deionized water was used to rinsethe residual premix into the flask. The batch was then held for twohours at temperature, and the batch was cooled. This yielded an emulsionat 34.0% solids, 14.5 acid number, pH of 5.45, and a viscosity 11.5 sec(Number 4 Ford Cup).

Stage E

To 50 parts of the emulsion from Stage D, 3.125 parts of a 50/50 blendof ethylene glycol and butyl cellosolve was added. This material wasapplied to chrome treated aluminum panels and baked for 10 seconds toachieve a 420° F. (217° C.) peak metal temperature. Results frombeverage end testing of this example versus a commercial control formulaare shown in Table 23.

TABLE 23 Waterbased Control¹ Example 6 MEK Resistance 22 11 Feathering⁴0.102 0.013 Pasteurization² Blush 10 9.5 Adhesion 10 10 Water Retort³Blush 10 10 Adhesion 10 10 End Continuity Initial 1.35 0.25Pasteurization² 2.38 1.35 ¹Commercially available beverage end coatingfrom Valspar coded 13Q80AG. ²30 minutes at 85° C. (185° F.). ³90 minutesat 121° C. (250° F.). ⁴Performed after 45 minutes at 85° C. (185° F.)pasteurization. Measured in centimeters.

Example 7 Emulsion for Inside Spray

A 3-liter flask was equipped with a stirrer, reflux condenser,thermocouple, heating mantle, and nitrogen blanket. Into the flask wasadded 392.2 parts of Example 1: Run 4 Acid Functional Acrylic, 86.4parts deionized water, 34.6 parts DMEA, and 1120.8 parts deionizedwater. The contents of the flask were heated to 70° C. In a separatevessel a premix of 215.8 parts styrene, 302.7 parts butyl acrylate, and42.0 parts glycidyl methacrylate was prepared. Once the flask was at 70°C., 5.5 parts benzoin and 27.8 parts deionized water was added, followedby 10% of the premix. The flask was heated further to 79° C. and whenthis temperature was reached 5.5 parts of 35% hydrogen peroxide and 27.8parts deionized water were added and held for five minutes. The flaskwas stirred at 210 rpm. After five minutes the temperature control wasset at 81° C. and the remaining premix was added over one hour. When theaddition was complete, 55.9 parts deionized water were used to rinse theresidual premix into the flask. The batch was held for ten minutes andthen 0.96 parts benzoin, 55.9 parts deionized water, and 0.95 parts 35%hydrogen peroxide were added. The batch was held for 45 minutes and then0.31 parts benzoin and 0.31 part 35% hydrogen peroxide were added. Aftertwo hours the batch was cooled to 45° C. Once at 45° C., 0.46 part ofHAMP-OL 4.5% Iron 2.98 parts TRIGONOX A-W70, and a premix of 2.1 partserythorbic acid, 0.91 parts DMEA, and 18.0 parts deionized water, wereadded. The batch was held at 45° C. for one hour. The material was thencooled to give an emulsion at 31.6% solids, 67.7 acid number, pH of7.04, and a viscosity of 84 seconds (Number 4 Ford cup).

Example 8 Spray Application

The water-based emulsion of Example 7 was successfully formulated into aspray applied coating for the interior of beer/beverage aluminum cans.The product was formulated as described in Table 24.

TABLE 24 Composition (parts) Example 8 Beverage Inside Spray CoatingComposition Example 7 material 62.8 Deionized Water 25.3 ButylCellosolve 5.1 Amyl Alcohol 3.1 Butanol 0.7 Deionized Water 3.0Additional Deionized Water to 18.5% Solids Formulation Solids, % 18.5%Viscosity, No. 4 Ford cup 46 Seconds

This formulation was sprayed at typical laboratory conditions at 120milligram per can (mg/can) to 130 mg/can coating weight for theapplication of interior beverage coatings, and cured at 188° C. to 199°C. (measured at the can dome) for 30 seconds through a gas oven conveyorat typical heat schedules for this application. The film propertiesshown in Table 25 were achieved.

TABLE 25 Inside Spray Film Properties Water-based Control¹ Example 8Metal Exposures Initial 2 mA 1 mA After drop damage 2 mA 5 mA Waterretort² Blush None None Adhesion Excellent Excellent ¹Commerciallyavailable inside beverage can coating from Valspar coded 10Q45AF. ²90minutes at 250° F. (121° C.)

As can be seen in Table 25, the coatings of the present inventioncompare favorably to the commercial epoxy-acrylate coating

Example 9 Latex with Polyester-Polyether Stabilizer

Example 9 illustrates the use of a different acid-functional polymersalt as the stabilizer for an emulsion of the present invention.

Stage A

A flask was equipped with a stirrer, packed column, Dean Stark trap,reflux condenser, thermocouple, heating mantle and nitrogen blanket. Tothe flask, 809.8 parts sebacic acid and 1283.0 parts CHDM-90 (90%1,4-cyclohexane dimethanol in water) were added. Under a nitrogenblanket, the contents were heated to distill the water from the CHDM-90.While the contents were heated at 165° C., 1.96 parts FASCAT 4100 wasadded. The temperature was increased to 220° C. to remove water. Asample of the batch was tested and found to have an acid number of 0.5.The remainder of the batch was weighed, and to 1711.7 parts of thismaterial were added 1040.2 parts of para-hydroxy benzoic acid. The batchwas heated to 230° C. to remove water. To aid in the removal of waterxylene was added incrementally. After two days of water removal, 1.04parts FASCAT 4100 was added to aid in the reaction. The reaction washeld an additional 5 hours and then considered complete. A portion ofthe product was used in Stage B.

Stage B

The material from Stage A (1915.2 parts) was placed in a flask alongwith 823.8 parts ERISYS GE-22 (cyclohexanedimethanol diglycidyl ether,84.8 parts methyl isobutyl ketone (, and 2.63 parts Catalyst 1201(ethyltriphenyl phosphonium iodide,). The temperature was set at 170° C.and the contents heated. After three hours at temperature, the epoxyvalue of the material was 0.003. The batch was adjusted to have 2684.2parts of this material in the flask. Added to the flask were 145.0 partsmethyl isobutyl ketone and 294.7 parts succinic anhydride. Thetemperature was maintained at 120-135° C. for two hours. After thetwo-hour hold, 124.8 parts deionized water and a premix of 214.2 partsDMEA with 265.8 parts deionized water were added. Then 6325.8 partsdeionized water was added. The material was cooled resulting in aproduct with 26.4% solids, an acid number of 71.9, a pH of 7.7, and aNumber 4 Ford viscosity of 15 seconds. This material was used in StageC.

Stage C

A 5-liter flask was equipped with a stirrer, reflux condenser,thermocouple, heating mantle, and nitrogen blanket. Into the flask wasadded 1183.4 parts of the Stage B material and 779.6 parts deionizedwater. A premix of 7.25 parts erythorbic acid, 6.5 parts DMEA, and 76.7parts deionized water was prepared. This initial premix and 0.18 partsHAMP-OL 4.5% Iron were added to the flask. The contents of the flaskwere heated to 30° C. In a separate vessel a monomer premix of 249.0parts styrene, 113.8 BA, 106.7 parts BMA, 177.8 parts Hydroxy EthylMethacrylate (HEMA), 35.6 parts IBMA, and 28.5 parts GMA was prepared. Athird premix of 7.25 parts TRIGONOX A-W70 and 82.2 parts deionized waterwere made. Once all the premixes were prepared and the flask at 30° C.,the stirrer was set at 240 rpm and all of the monomer premix was added.The monomer premix vessel was rinsed with 81.6 parts deionized water,which was also added to the flask. The contents of the flask werestirred for 10 minutes, after which 10% of the third premix was addedwithin one minute. Once the 10% of the third premix was in, thetemperature was increased to 37° C. and the batch was held for fiveminutes. After five minutes, the remaining amount of the third premixwas added over 45 minutes. The temperature was allowed to increase withno external heat applied. During the addition the maximum temperaturewas 57° C. After the addition was complete the temperature was 51° C.Temperature control was set for 52° C. The third premix was rinsed with108.4 parts deionized water and added to the batch. The batch was heldfor 1.5 hours and then cooled. This yielded an emulsion at 33.1% solids,27.1 acid number, pH of 7.9, and a viscosity 12 sec (Number 4 Ford Cup).

Stage D

To 1473.75 parts of the emulsion from Stage C, 26.25 parts DMEOA wereadded to increase the pH to 8.6. Using 1330.18 parts of this increasedpH material, 89.51 parts ethylene glycol, 16.65 parts dibasic ester,16.67 parts DOWANOL PM, 5.17 parts xylene, 17.5 parts of a 50% solidssolution of a phenol-formaldehyde phenolic, and 24.57 parts MICHEM 160PFE were added. This formulation was determined to be 30.1% solids, 12seconds Number 4 Ford viscosity and 8.75 pounds per gallon (1.05 kg/l).

The Stage D composition was applied to non-chrome aluminum panels andbaked for 10 seconds to achieve a 420° F. (215° C.) peak metaltemperature. A second set was baked for 10 seconds to achieve a 440° F.(227° C.) peak metal temperature. Results from beverage end testing ofthis example versus a commercial water base and solvent base controlformulas are shown in Tables 26 and 27.

TABLE 26 Comparative Testing of Example 9 Stage D Cured at 420° F. (215°C.) Solvent-based Example 9 Water-based Control¹ Control² Stage D MEK 4434 38 Feathering³ 0.0457 0.0457 0.000 COF 0.061 0.066 0.063Pasteurization⁴ Blush 10 10 8 to 9⁶ Adhesion 10 10 10 Water Retort⁵Blush 10 10  4 to 10⁶ Adhesion 10 10 End Continuity Initial AfterInitial After Intial After Pasteurization 0.08 0.12 0.0 0.30 0.0 0.5Water Retort 0.10 0.4 0.02 0.72 0.27 1.2 ¹Commercially availablebeverage end coating from Valspar coded 13Q80AG. ²Commercially availablebeverage end coating from Valspar coded 92X205S. ³Performed after 45minutes at 85° C. (185° F.) pasteurization. Measured in centimeters(cm). ⁴30 minutes at 85° C. (185° F.). ⁵90 minutes at 121° C. (250° F.).⁶Initial Blush seen which improves within 5 minutes.

TABLE 27 Comparative Testing of Example 9 Stage D Cured at 440° F. (227°C.) Solvent-based Example 9 Water-based Control¹ Control² Stage D MEK 5237 40 Feathering³ 0.0559 0.0356 0.000 COF 0.059 0.065 0.063Pasteurization⁴ Blush 10 10 8 to 10⁶ Adhesion 10 10 10 Water Retort⁵Blush 10 10 6 to 10⁶ Adhesion 10 10 End Continuity Initial After InitialAfter Intial After Pasteurization 0.0 0.48 0.07 0.23 0.1 0.8 WaterRetort 0.05 0.4 0.25 1.5 0.35 0.8 ¹Commercially available beverage endcoating from Valspar coded 13Q80AG. ²Commercially available beverage endcoating from Valspar coded 92X205S. ³Performed after 45 minutes at 85°C. (185° F.) pasteurization. Measured in cm. ⁴30 minutes at 85° C. (185°F.). ⁵90 minutes at 121° C. (250° F.). ⁶Initial Blush seen whichimproves within 5 minutes.

Example 10

Example 10 illustrates the use of a different acid-functional polymersalt as the stabilizer for an emulsion of the present invention.

Stage 1

Approximately 1055 parts BPA is placed in a flask along withapproximately 1684 parts of liquid epoxy resin (EPON 828), 85 partsmethyl isobutyl ketone, and 2 to 3 parts Catalyst 1201. The temperatureis set at 160° C. and the contents are then heated for approximatelythree hours to achieve an epoxy value of the material of approximately0.003. The batch is then adjusted to have 2684.2 parts of this materialin the flask. Added to the flask is 145.0 parts methyl isobutyl ketoneand 294.7 parts succinic anhydride. The temperature is maintained at120-135° C. for two hours. After the two-hour hold, 124.8 partsdeionized water and a premix of 214.2 parts DMEA with 265.8 partsdeionized water is added. Then 6325.8 parts deionized water is added.The material is cooled, and should result in a product with targetvalues of 26% to 27% solids, an acid number of approximately 72, a pH ofapproximately 7 to 9, and a Number 4 Ford viscosity of 15 Seconds. Thismaterial is used in Stage 2.

Stage 2

A 5-liter flask is equipped with a stirrer, reflux condenser,thermocouple, heating mantle, and nitrogen blanket. Into the flask isadded approximately 1183 parts of the Stage 1 material and 780 partsdeionized water. A premix of 7.25 parts erythorbic acid, 6.5 parts DMEA,and 77 parts deionized water is prepared. This initial premix and 0.18parts HAMP-OL 4.5% Iron are added to the flask. The contents of theflask are heated to 30° C. In a separate vessel a monomer premix of 249parts styrene, 114 BA, 107 parts BMA, 178 parts HEMA, 36 parts IBMA, and28 parts GMA is prepared. A third premix of 7.25 parts TRIGONOX A-W70and 82.2 parts deionized water is made. Once all the premixes areprepared and the flask is at 30° C., the stirrer is set at 240 rpm andall of the monomer premix is added. The monomer premix vessel is rinsedwith 82 parts deionized water, which is also added to the flask. Thecontents of the flask are stirred for 10 minutes, after which 10% of thethird premix is added within one minute. Once the 10% is in thetemperature is increased to 37° C. The batch is held for five minutes.After five minutes, the remaining amount of the third premix is addedover 45 minutes. The temperature is allowed to increase with no externalheat applied. During the addition the maximum temperature is 57° C.After the addition is complete the temperature is set for 52° C. Thethird premix is rinsed with 109 parts deionized water and added to thebatch. The batch is held for 1.5 hours and cooled. This process shouldyield an emulsion with a target of approximately 33% solids, 27 acidnumber, pH of 8, and a viscosity of 12 sec (Number 4 Ford Cup).

Stage 3

To 1474 parts of the emulsion from Stage 2, 26.25 parts DMEOA is addedto increase the pH to 8.6. Using 1330.18 parts of this increased pHmaterial, 89.51 parts ethylene glycol, 16.65 parts dibasic ester, 16.67parts Dowanol PM, 5.17 parts xylene, 17.5 parts of a 50% solids solutionof a phenol-formaldehyde phenolic, and 24.57 parts Michem 160 PFE isadded. This formulation should yield a composition having approximately30% solids.

The Stage 3 composition may be applied to non-chrome aluminum panels andbaked for 10 seconds to achieve a 217° C. peak metal temperature.

The complete disclosures of the patents, patent documents, andpublications cited herein are incorporated by reference in theirentirety as if each were individually incorporated. Variousmodifications and alterations to this invention will become apparent tothose skilled in the art without departing from the scope and spirit ofthis invention. It should be understood that this invention is notintended to be unduly limited by the illustrative embodiments andexamples set forth herein and that such examples and embodiments arepresented by way of example only with the scope of the inventionintended to be limited only by the claims set forth herein as follows.

1. A method of coating a food or beverage can, the method comprising:forming a composition comprising an emulsion polymerized latex polymer,comprising: forming a salt of an acid- or anhydride-functional polymerand an amine in a carrier comprising water to form an aqueousdispersion; combining an ethylenically unsaturated monomer componentwith the aqueous dispersion; and polymerizing the ethylenicallyunsaturated monomer component in the presence of the aqueous dispersionto form an emulsion polymerized latex polymer that is substantially freeof bound bisphenol A and aromatic glycidyl ether compounds; and applyingthe composition comprising the emulsion polymerized latex polymer to ametal substrate prior to or after forming the metal substrate into afood or beverage can or portion thereof.
 2. The method of claim 1wherein applying the composition to a metal substrate comprises applyingthe composition to the metal substrate in the form of a planar coil orsheet, hardening the emulsion polymerized latex polymer, and forming thesubstrate into a food or beverage can or portion thereof.
 3. The methodof claim 2 wherein forming the substrate into a can or portion thereofcomprises forming the substrate into a can end or a can body.
 4. Themethod of claim 2 wherein the can is a 2-piece drawn food can, 3-piecefood can, food can end, drawn and ironed can, or beverage can end. 5.The method of claim 1 wherein the metal substrate comprises steel oraluminum.
 6. The method of claim 1 wherein applying the composition to ametal substrate comprises applying the composition to the metalsubstrate after the metal substrate is formed into a can or portionthereof.
 7. The method of claim 1 wherein combining an ethylenicallyunsaturated monomer component with the aqueous dispersion comprisesadding the ethylenically unsaturated monomer component to the aqueousdispersion.
 8. The method of claim 7 wherein the ethylenicallyunsaturated monomer component is added incrementally to the aqueousdispersion.
 9. The method of claim 1 wherein the ethylenicallyunsaturated monomer component comprises a mixture of monomers.
 10. Themethod of claim 9 wherein the mixture of monomers comprises at least oneoxirane functional group-containing monomer.
 11. The method of claim 10wherein the mixture of monomers comprises at least one oxiranefunctional group-containing alpha, beta-ethylenically unsaturatedmonomer.
 12. The method of claim 10 wherein the oxirane functionalgroup-containing monomer is present in the ethylenically unsaturatedmonomer component in an amount of at least 0.1 wt-%, based on the weightof the monomer mixture.
 13. The method of claim 10 wherein the oxiranefunctional group-containing monomer is present in the ethylenicallyunsaturated monomer component in an amount of no greater than 30 wt-%,based on the weight of the monomer mixture.
 14. The method of claim 1further comprising combining the emulsion polymerized latex polymer withone or more crosslinkers, fillers, catalysts, dyes, pigments, toners,extenders, lubricants, anticorrosion agents, flow control agents,thixotropic agents, dispersing agents, antioxidants, adhesion promoters,light stabilizers, organic solvents, surfactants, or combinationsthereof in the coating composition.
 15. The method of claim 1 whereinthe acid- or anhydride-functional polymer has a number average molecularweight of 1500 to 50,000.
 16. The method of claim 1 wherein thecomposition is substantially free of mobile bisphenol A and aromaticglycidyl ether compounds.
 17. The method of claim 16 wherein thecomposition is substantially free of bound bisphenol A and aromaticglycidyl ether compounds.
 18. The method of claim 1 wherein the acid- oranhydride-functional polymer comprises an acid- or anhydride-functionalacrylic polymer, acid- or anhydride-functional alkyd resin, acid- oranhydride-functional polyester resin, acid- or anhydride-functionalpolyurethane, or combinations thereof.
 19. The method of claim 18wherein the acid- or anhydride-functional polymer comprises anacid-functional acrylic polymer.
 20. The method of claim 18 wherein theacid- or anhydride-functional polymer comprises a polyester polymer. 21.The method of claim 20 wherein the polyester polymer comprises one ormore segments of Formula I:—O—Ar—R_(n)—C(O)—O—R¹—O—C(O)—R_(n)—Ar—O— wherein: each Ar isindependently a divalent aryl group or heteroarylene group; each R isindependently a divalent organic group; R¹ is a divalent organic group;and each n is 0 or
 1. 22. The method of claim 1 wherein the amine is atertiary amine.
 23. The method of claim 22 wherein the tertiary amine isselected from the group consisting of trimethyl amine, dimethylethanolamine, methyldiethanol amine, triethanol amine, ethyl methyl ethanolamine, dimethyl ethyl amine, dimethyl propyl amine, dimethyl3-hydroxy-1-propyl amine, dimethylbenzyl amine, dimethyl2-hydroxy-1-propyl amine, diethyl methyl amine, dimethyl1-hydroxy-2-propyl amine, triethyl amine, tributyl amine, N-methylmorpholine, and mixtures thereof.
 24. The method of claim 1 wherein theacid- or anhydride-functional polymer is at least 25% neutralized withthe amine in water.
 25. The method of claim 1 wherein the ethylenicallyunsaturated monomer component is polymerized in the presence of theaqueous dispersion with a water-soluble free radical initiator at atemperature of 0° C. to 100° C.
 26. The method of claim 25 wherein thefree radical initiator comprises a peroxide initiator.
 27. The method ofclaim 25 wherein the free radical initiator comprises hydrogen peroxideand benzoin.
 28. The method of claim 25 wherein the free radicalinitiator comprises a redox initiator system.
 29. The method of claim 1wherein the aqueous dispersion further comprises an organic solvent. 30.The method of claim 29 further comprising removing at least a portion ofthe organic solvent prior to forming the emulsion polymerized latexpolymer.
 31. The method of claim 1, wherein the composition is appliedto a food-contact surface of the metal substrate.
 32. A method ofcoating a food or beverage can, the method comprising: forming acomposition comprising an emulsion polymerized latex polymer,comprising: forming a salt of an acid- or anhydride-functional polymerand a tertiary amine in a carrier comprising water to form an aqueousdispersion; combining an ethylenically unsaturated monomer componentcomprising 0.1 wt-% to 30 wt-% of an oxirane-functional alpha,beta-ethylenically unsaturated monomer with the aqueous dispersion,based on the weight of the monomer component; and polymerizing theethylenically unsaturated monomer component in the presence of theaqueous dispersion to form an emulsion polymerized latex polymer; andapplying the composition comprising the emulsion polymerized latexpolymer to a metal substrate prior to or after forming the metalsubstrate into a food or beverage can or portion thereof.